[management, client, proxy] Follow-up fixes for private reverse-proxy services (#6268)

* fix(proxy): gate tunnel-peer fast-path on inbound listener marker

forwardWithTunnelPeer previously accepted any RFC1918 / ULA / CGNAT
source IP, so a public client whose address happened to fall in those
ranges could bypass the configured operator auth scheme by colliding
with a known tunnel IP. The fast-path is now gated on
TunnelLookupFromContext(r.Context()) being present — that context value
is attached only by the per-account inbound (overlay) listener, so the
host-facing listener never enters this branch.

Tests updated to reflect the new requirement: requests that don't
carry the inbound marker now fall through to the regular auth flow.

* fix(proxy): harden inbound listener resource + startup-ctx handling

Three correctness fixes on the per-account inbound path, with tests:

- Close the logrus ErrorLog PipeWriter on tearDown. WriterLevel hands
  back an *io.PipeWriter backed by a pipe + scanner goroutine that the
  caller owns; the two writers per account (https + plain) were never
  closed, leaking the pipe and goroutine on every teardown.
- Run the post-Start hooks on context.Background(). runClientStartup
  is launched in a goroutine from AddPeer and was inheriting the
  caller's request-scoped ctx, so a cancelled request could abort the
  inbound bring-up or fail the management status notification. The
  tail is split into notifyClientReady so the contract is testable.

Tests cover the PipeWriter close behaviour and assert the readyHandler
+ NotifyStatus calls receive a non-cancelled background context.

* feat(proxy): short-circuit peer-own-target loops with 421

When a peer that hosts the target of a private service dials its own
service URL the request was being looped through the proxy and back
over WireGuard to the same peer — twice the WG round-trip for no
benefit, with no signal to the caller that something was wrong.

Add isSelfTargetLoop to ReverseProxy.ServeHTTP: when the request
arrived on the per-account overlay listener (IsOverlayOrigin) and the
source tunnel IP matches the target host, refuse the request with 421
Misdirected Request and a body pointing the operator at the backend
directly.

The gate is scoped to overlay origin so requests on the public
listener that happen to share a source IP with the target host are
forwarded normally.

* fix(management): private-service validation + tunnel-IP lookup semantics

- Require an explicit port for L4 cluster targets. validateL4Target
  exempted TargetTypeCluster from the port check, but buildPathMappings
  serializes every L4 target via net.JoinHostPort(host, port) — port=0
  shipped a ":0" upstream. Cluster targets use the same Host/Port
  fields, so the same requirement applies.
- GetPeerByIP returns NotFound on a tunnel-IP miss instead of mapping
  every error to Internal. The proxy's ValidateTunnelPeer probes IPs
  that legitimately aren't in the roster; the miss is expected and now
  distinguishable from a real store failure.
- Thread ctx into getClusterCapability's gorm query so a cancelled
  request doesn't keep the store busy.

Tests updated for the L4-cluster port requirement and the GetPeerByIP
NotFound path.

* fix(client): include offlinePeers in PeerStateByIP lookup

ReplaceOfflinePeers moves peers into d.offlinePeers but PeerStateByIP
only scanned d.peers. Callers (the local DNS filter via
localPeerConnectivity, embed.Client.IdentityForIP used by the
proxy's tunnel-peer validator) were treating known-but-offline peers
as unknown, which:

- causes the DNS filter to keep returning records pointing at peers
  that have no live tunnel, AND
- makes the proxy's local-roster check deny a request from such a
  peer rather than letting the cached management RPC carry the
  authorisation decision.

Search both slices in PeerStateByIP. Adds a unit test for the IPv4
and IPv6 offline-match paths.

* fix(rest): reject empty Delete path params in reverse-proxy clients

ReverseProxyClustersAPI.Delete and ReverseProxyTokensAPI.Delete passed
the path parameter into url.PathEscape without an empty check.
PathEscape("") returns "" which collapses the request onto the
collection endpoint ("/api/reverse-proxies/clusters/" /
"/api/reverse-proxies/proxy-tokens/"), so a caller bug delete with no
id reached a routable URL with surprising semantics (typically 405).

Short-circuit with a typed error before the request is built. Tests
mount a handler on the collection path that fails the test if hit, so
the regression is impossible to reintroduce silently.

* chore(api,ci,docs,test): private-service schema, proto-check, fixups

Non-functional cleanups and contract/CI hardening around the
private-service work:

API schema (openapi.yml):
- Require a non-empty access_groups and mode=http when private=true,
  on both Service and ServiceRequest, mirroring
  validatePrivateRequirements. mode stays optional-but-constrained
  (empty defaults to http server-side), matching runtime.

CI (proto-version-check.yml):
- Cover renamed .pb.go files (read base via previous_filename).
- Match protoc-gen-go-grpc version headers (optional "- " prefix and
  -gen-go-grpc suffix) so grpc-generated files are in scope.

Docs / comments:
- Reword Config field docs to say defaults are applied at Server.Start
  (initDefaults), not New.
- Rename the obsolete --private-inbound flag to --private across
  comments and the proto doc.

Pre-existing test fixups surfaced by review:
- Repair the integration-tagged validate_session_test.go (SignToken
  signature growth + new Manager interface methods).
- Fix the CI-skip boolean precedence so Windows isn't skipped
  unconditionally.
- Guard the router.HTTPListener type assertion with comma-ok.

* fix(proxy): background ctx for already-started AddPeer notification

The earlier ctx fix covered the async runClientStartup path but missed
the synchronous branch: when a service is added to an already-started
client, AddPeer called NotifyStatus with the caller's request-scoped
ctx. A cancelled request/stream could drop the connected notification
to management. Use context.Background() here too, matching
notifyClientReady.

Extends TestNetBird_AddPeer_ExistingStartedClient_NotifiesStatus to
pass a pre-cancelled caller ctx and assert the notification still ran
on a non-cancelled context.

* use the cmd context for roundtripper

.github/workflows/proto-version-check.yml

@@ -20,15 +20,30 @@ jobs:
               per_page: 100,
             });
 
-            const modifiedPbFiles = files.filter(
-              f => f.filename.endsWith('.pb.go') && f.status === 'modified'
-            );
-            if (modifiedPbFiles.length === 0) {
-              console.log('No modified .pb.go files to check');
+            // Cover renamed .pb.go files in addition to plain edits.
+            // Renamed entries land under the new path with previous_filename
+            // pointing at the base-side name, so we read the base content
+            // from the old path when present.
+            const changedPbFiles = files
+              .filter(f => (f.status === 'modified' || f.status === 'renamed')
+                && f.filename.endsWith('.pb.go'))
+              .map(f => ({
+                headPath: f.filename,
+                basePath: f.previous_filename || f.filename,
+              }));
+            if (changedPbFiles.length === 0) {
+              console.log('No modified or renamed .pb.go files to check');
               return;
             }
 
-            const versionPattern = /^\s*\/\/\s+protoc(?:-gen-go)?\s+v[\d.]+/;
+            // Matches the generator version headers protoc writes at the top
+            // of generated files:
+            //   //   protoc           v3.21.12
+            //   //   protoc-gen-go    v1.26.0
+            //   // - protoc-gen-go-grpc v1.6.1   (grpc files prefix with "- ")
+            // The optional "- " prefix and the optional -gen-go / -gen-go-grpc
+            // suffixes keep the *_grpc.pb.go headers in scope.
+            const versionPattern = /^\s*\/\/\s+(?:-\s+)?protoc(?:-gen-go(?:-grpc)?)?\s+v[\d.]+/;
             const baseSha = context.payload.pull_request.base.sha;
             const headSha = context.payload.pull_request.head.sha;
 
@@ -55,20 +70,22 @@ jobs:
             }
 
             const violations = [];
-            for (const file of modifiedPbFiles) {
+            for (const file of changedPbFiles) {
               const [base, head] = await Promise.all([
-                getVersionHeader(file.filename, baseSha),
-                getVersionHeader(file.filename, headSha),
+                getVersionHeader(file.basePath, baseSha),
+                getVersionHeader(file.headPath, headSha),
               ]);
               if (!base.ok || !head.ok) {
                 core.warning(
-                  `Skipping ${file.filename}: base=${base.ok ? 'ok' : base.reason}, head=${head.ok ? 'ok' : head.reason}`
+                  `Skipping ${file.headPath}: base=${base.ok ? 'ok' : base.reason}, head=${head.ok ? 'ok' : head.reason}`
                 );
                 continue;
               }
               if (base.lines.join('\n') !== head.lines.join('\n')) {
                 violations.push({
-                  file: file.filename,
+                  file: file.basePath === file.headPath
+                    ? file.headPath
+                    : `${file.basePath} → ${file.headPath}`,
                   base: base.lines,
                   head: head.lines,
                 });