feat(private-service): expose NetBird-only services over tunnel peers

Adds a new "private" service mode for the reverse proxy: services
reachable exclusively over the embedded WireGuard tunnel, gated by
per-peer group membership instead of operator auth schemes.

Wire contract
- ProxyMapping.private (field 13): the proxy MUST call
  ValidateTunnelPeer and fail closed; operator schemes are bypassed.
- ProxyCapabilities.private (4) + supports_private_service (5):
  capability gate. Management never streams private mappings to
  proxies that don't claim the capability; the broadcast path applies
  the same filter via filterMappingsForProxy.
- ValidateTunnelPeer RPC: resolves an inbound tunnel IP to a peer,
  checks the peer's groups against service.AccessGroups, and mints
  a session JWT on success. checkPeerGroupAccess fails closed when
  a private service has empty AccessGroups.
- ValidateSession/ValidateTunnelPeer responses now carry
  peer_group_ids + peer_group_names so the proxy can authorise
  policy-aware middlewares without an extra management round-trip.
- ProxyInboundListener + SendStatusUpdate.inbound_listener: per-account
  inbound listener state surfaced to dashboards.
- PathTargetOptions.direct_upstream (11): bypass the embedded NetBird
  client and dial the target via the proxy host's network stack for
  upstreams reachable without WireGuard.

Data model
- Service.Private (bool) + Service.AccessGroups ([]string, JSON-
  serialised). Validate() rejects bearer auth on private services.
  Copy() deep-copies AccessGroups. pgx getServices loads the columns.
- DomainConfig.Private threaded into the proxy auth middleware.
  Request handler routes private services through forwardWithTunnelPeer
  and returns 403 on validation failure.
- Account-level SynthesizePrivateServiceZones (synthetic DNS) and
  injectPrivateServicePolicies (synthetic ACL) gate on
  len(svc.AccessGroups) > 0.

Proxy
- /netbird proxy --private (embedded mode) flag; Config.Private in
  proxy/lifecycle.go.
- Per-account inbound listener (proxy/inbound.go) binding HTTP/HTTPS
  on the embedded NetBird client's WireGuard tunnel netstack.
- proxy/internal/auth/tunnel_cache: ValidateTunnelPeer response cache
  with single-flight de-duplication and per-account eviction.
- Local peerstore short-circuit: when the inbound IP isn't in the
  account roster, deny fast without an RPC.
- proxy/server.go reports SupportsPrivateService=true and redacts the
  full ProxyMapping JSON from info logs (auth_token + header-auth
  hashed values now only at debug level).

Identity forwarding
- ValidateSessionJWT returns user_id, email, method, groups,
  group_names. sessionkey.Claims carries Email + Groups + GroupNames
  so the proxy can stamp identity onto upstream requests without an
  extra management round-trip on every cookie-bearing request.
- CapturedData carries userEmail / userGroups / userGroupNames; the
  proxy stamps X-NetBird-User and X-NetBird-Groups on r.Out from the
  authenticated identity (strips client-supplied values first to
  prevent spoofing).
- AccessLog.UserGroups: access-log enrichment captures the user's
  group memberships at write time so the dashboard can render group
  context without reverse-resolving stale memberships.

OpenAPI/dashboard surface
- ReverseProxyService gains private + access_groups; ReverseProxyCluster
  gains private + supports_private. ReverseProxyTarget target_type
  enum gains "cluster". ServiceTargetOptions gains direct_upstream.
  ProxyAccessLog gains user_groups.

management/internals/modules/reverseproxy/proxy/manager.go

@@ -19,6 +19,7 @@ type Manager interface {
 	ClusterSupportsCustomPorts(ctx context.Context, clusterAddr string) *bool
 	ClusterRequireSubdomain(ctx context.Context, clusterAddr string) *bool
 	ClusterSupportsCrowdSec(ctx context.Context, clusterAddr string) *bool
+	ClusterSupportsPrivate(ctx context.Context, clusterAddr string) *bool
 	CleanupStale(ctx context.Context, inactivityDuration time.Duration) error
 	GetAccountProxy(ctx context.Context, accountID string) (*Proxy, error)
 	CountAccountProxies(ctx context.Context, accountID string) (int64, error)

management/internals/modules/reverseproxy/proxy/manager/manager.go

@@ -21,6 +21,7 @@ type store interface {
 	GetClusterSupportsCustomPorts(ctx context.Context, clusterAddr string) *bool
 	GetClusterRequireSubdomain(ctx context.Context, clusterAddr string) *bool
 	GetClusterSupportsCrowdSec(ctx context.Context, clusterAddr string) *bool
+	GetClusterSupportsPrivate(ctx context.Context, clusterAddr string) *bool
 	CleanupStaleProxies(ctx context.Context, inactivityDuration time.Duration) error
 	GetProxyByAccountID(ctx context.Context, accountID string) (*proxy.Proxy, error)
 	CountProxiesByAccountID(ctx context.Context, accountID string) (int64, error)
@@ -137,6 +138,11 @@ func (m Manager) ClusterSupportsCrowdSec(ctx context.Context, clusterAddr string
 	return m.store.GetClusterSupportsCrowdSec(ctx, clusterAddr)
 }
 
+// ClusterSupportsPrivate reports whether any active proxy claims the private capability (nil = unreported).
+func (m Manager) ClusterSupportsPrivate(ctx context.Context, clusterAddr string) *bool {
+	return m.store.GetClusterSupportsPrivate(ctx, clusterAddr)
+}
+
 // CleanupStale removes proxies that haven't sent heartbeat in the specified duration
 func (m *Manager) CleanupStale(ctx context.Context, inactivityDuration time.Duration) error {
 	if err := m.store.CleanupStaleProxies(ctx, inactivityDuration); err != nil {
@@ -178,4 +184,3 @@ func (m *Manager) DeleteAccountCluster(ctx context.Context, clusterAddress, acco
 	}
 	return nil
 }
-

management/internals/modules/reverseproxy/proxy/manager/manager_test.go

@@ -15,16 +15,16 @@ import (
 )
 
 type mockStore struct {
-	saveProxyFunc                              func(ctx context.Context, p *proxy.Proxy) error
-	disconnectProxyFunc                        func(ctx context.Context, proxyID, sessionID string) error
-	updateProxyHeartbeatFunc                   func(ctx context.Context, p *proxy.Proxy) error
-	getActiveProxyClusterAddressesFunc         func(ctx context.Context) ([]string, error)
-	getActiveProxyClusterAddressesForAccFunc   func(ctx context.Context, accountID string) ([]string, error)
-	cleanupStaleProxiesFunc                    func(ctx context.Context, d time.Duration) error
-	getProxyByAccountIDFunc                    func(ctx context.Context, accountID string) (*proxy.Proxy, error)
-	countProxiesByAccountIDFunc                func(ctx context.Context, accountID string) (int64, error)
-	isClusterAddressConflictingFunc            func(ctx context.Context, clusterAddress, accountID string) (bool, error)
-	deleteAccountClusterFunc                   func(ctx context.Context, clusterAddress, accountID string) error
+	saveProxyFunc                            func(ctx context.Context, p *proxy.Proxy) error
+	disconnectProxyFunc                      func(ctx context.Context, proxyID, sessionID string) error
+	updateProxyHeartbeatFunc                 func(ctx context.Context, p *proxy.Proxy) error
+	getActiveProxyClusterAddressesFunc       func(ctx context.Context) ([]string, error)
+	getActiveProxyClusterAddressesForAccFunc func(ctx context.Context, accountID string) ([]string, error)
+	cleanupStaleProxiesFunc                  func(ctx context.Context, d time.Duration) error
+	getProxyByAccountIDFunc                  func(ctx context.Context, accountID string) (*proxy.Proxy, error)
+	countProxiesByAccountIDFunc              func(ctx context.Context, accountID string) (int64, error)
+	isClusterAddressConflictingFunc          func(ctx context.Context, clusterAddress, accountID string) (bool, error)
+	deleteAccountClusterFunc                 func(ctx context.Context, clusterAddress, accountID string) error
 }
 
 func (m *mockStore) SaveProxy(ctx context.Context, p *proxy.Proxy) error {
@@ -99,6 +99,9 @@ func (m *mockStore) GetClusterRequireSubdomain(_ context.Context, _ string) *boo
 func (m *mockStore) GetClusterSupportsCrowdSec(_ context.Context, _ string) *bool {
 	return nil
 }
+func (m *mockStore) GetClusterSupportsPrivate(_ context.Context, _ string) *bool {
+	return nil
+}
 
 func newTestManager(s store) *Manager {
 	meter := noop.NewMeterProvider().Meter("test")

management/internals/modules/reverseproxy/proxy/manager_mock.go

@@ -92,6 +92,20 @@ func (mr *MockManagerMockRecorder) ClusterSupportsCrowdSec(ctx, clusterAddr inte
 	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "ClusterSupportsCrowdSec", reflect.TypeOf((*MockManager)(nil).ClusterSupportsCrowdSec), ctx, clusterAddr)
 }
 
+// ClusterSupportsPrivate mocks base method.
+func (m *MockManager) ClusterSupportsPrivate(ctx context.Context, clusterAddr string) *bool {
+	m.ctrl.T.Helper()
+	ret := m.ctrl.Call(m, "ClusterSupportsPrivate", ctx, clusterAddr)
+	ret0, _ := ret[0].(*bool)
+	return ret0
+}
+
+// ClusterSupportsPrivate indicates an expected call of ClusterSupportsPrivate.
+func (mr *MockManagerMockRecorder) ClusterSupportsPrivate(ctx, clusterAddr interface{}) *gomock.Call {
+	mr.mock.ctrl.T.Helper()
+	return mr.mock.ctrl.RecordCallWithMethodType(mr.mock, "ClusterSupportsPrivate", reflect.TypeOf((*MockManager)(nil).ClusterSupportsPrivate), ctx, clusterAddr)
+}
+
 // Connect mocks base method.
 func (m *MockManager) Connect(ctx context.Context, proxyID, sessionID, clusterAddress, ipAddress string, accountID *string, capabilities *Capabilities) (*Proxy, error) {
 	m.ctrl.T.Helper()

management/internals/modules/reverseproxy/proxy/proxy.go

@@ -20,6 +20,11 @@ type Capabilities struct {
 	RequireSubdomain *bool
 	// SupportsCrowdsec indicates whether this proxy has CrowdSec configured.
 	SupportsCrowdsec *bool
+	// Private indicates whether this proxy is embedded in a netbird client
+	// and serves exclusively over the WireGuard tunnel (i.e. `netbird proxy`
+	// rather than the standalone netbird-proxy binary). Surfaces upstream
+	// so dashboards can distinguish per-peer / private clusters.
+	Private *bool
 }
 
 // Proxy represents a reverse proxy instance
@@ -67,10 +72,10 @@ type Cluster struct {
 	Type             ClusterType
 	Online           bool
 	ConnectedProxies int
-	// Capability flags. *bool because nil means "no proxy reported a
-	// capability for this cluster" — the dashboard renders these as
-	// unknown rather than false.
+	// *bool: nil = no proxy reported the capability; the dashboard renders that as unknown.
 	SupportsCustomPorts *bool
 	RequireSubdomain    *bool
 	SupportsCrowdSec    *bool
+	// Private is true when at least one connected proxy reported the embedded-`netbird proxy` capability.
+	Private *bool
 }