[management,proxy] Agent network: per-account LLM gateway (policy, metering, multi-provider) (#6555)

* [agent-network] Shared proto, OpenAPI schema, and generated types

* [agent-network] Management: store, manager, synthesizer, policy engine, provider catalog, HTTP/gRPC API

Adds the account-scoped agent-network module: provider/policy/budget CRUD and
store, the reverse-proxy service synthesizer, policy selection + limit
enforcement, the provider catalog (incl. Vertex AI and AWS Bedrock entries),
and the management HTTP + proxy gRPC surfaces.

* [management] Fix agent-network proxy-peer fan-out on affected-peer recompute

The affected-peers resolver loaded only persisted reverse-proxy services, but
agent-network services are synthesized on demand and never persisted. As a
result the embedded proxy peer was never folded into the affected set when a
client's group changed, so the proxy received no network-map update for a newly
authorised client and rejected its handshake until a full resync (restart).

loadProxyServices now merges the synthesized agent-network services (injected
via a registration hook to avoid an import cycle), so proxy peers learn newly
authorised clients immediately.

* [proxy] Reverse-proxy middleware framework, chain, and request plumbing

The per-target middleware chain (slots, dispatcher, mutation gate, metadata
merger), body capture, access-log terminal sink, and the proxy wiring that
builds + runs chains for synthesized agent-network services.

* [proxy] LLM parsers, pricing, and builtin middlewares (OpenAI, Anthropic, Vertex AI, AWS Bedrock)

Request/response parsers and SSE/event-stream metering, the embedded pricing
table, and the builtin middleware set: request parser, router, policy
limit-check/record, cost meter, guardrail, identity inject, response parser.
Includes the path-routed providers — Google Vertex AI (keyfile:: service-account
OAuth minting) and AWS Bedrock (bearer auth, invoke/converse/streaming, optional
/bedrock prefix) — plus the Models allowlist and unmeterable-publisher deny.

* [proxy] IPv6 in-place apply and TCP accept-loop hardening on netstack listeners

* [agent-network] End-to-end test suite, module docs, and deployment preset

* [agent-network] Fix codespell typos and exclude false positives

- labelgen word pool: vermillion -> vermilion, racoon -> raccoon.
- codespell ignore list: add flate (Go compress/flate package), recordin
  (a test-local identifier), and unparseable (a valid alternative spelling used
  consistently across identifiers + a metadata-value constant).

* [management] Set LastSeen on injected proxy peer in realstack test (MySQL strict-mode)

The injected embedded proxy peer had a PeerStatus with a zero LastSeen, which
serializes to '0000-00-00' and is rejected by MySQL in strict mode (SQLite
tolerates it). Set LastSeen to a valid time so SaveAccount succeeds on both
engines.

* [agent-network] Remove e2e shell-script suite from this branch

The end-to-end shell scripts under scripts/e2e/ are maintained in a separate
testing suite and are not part of this change set.

* [agent-network] Polish module docs: remove internal review scaffolding, fix links, verify diagrams

Strip PR-review framing, commit references, absolute paths, and stale internal
references from the agent-network module docs; fix broken relative links; verify
all diagrams against the current architecture. Remove the internal AI-reviewer
prompt file.

* [management] Refine session expiration handling to support 3-state encoding for SSO deadlines

* [agent-network] Relocate agentnetwork package to internals/modules

Move management/server/agentnetwork (and its catalog/, labelgen/, types/
subpackages) to management/internals/modules/agentnetwork, alongside the
reverse-proxy module, and rewrite all importers. Pure relocation: package names,
the synthesizer + affectedpeers registration hook, and store access (shared
store.Store) are unchanged, so no import cycle is introduced (affectedpeers
still depends only on the agentnetwork/types leaf).

* [agent-network] Co-locate HTTP handlers in the module (RegisterEndpoints)

Move the agent-network HTTP handlers from server/http/handlers/agentnetwork into
the module at internals/modules/agentnetwork/handlers (package handlers) and
rename the entrypoint AddEndpoints -> RegisterEndpoints, matching the
reverse-proxy module convention. Wiring in http/handler.go updated accordingly.

management/internals/modules/peers/manager.go

@@ -220,12 +220,36 @@ func (m *managerImpl) GetPeerID(ctx context.Context, peerKey string) (string, er
 func (m *managerImpl) CreateProxyPeer(ctx context.Context, accountID string, peerKey string, cluster string) error {
 	existingPeerID, err := m.store.GetPeerIDByKey(ctx, store.LockingStrengthNone, peerKey)
 	if err == nil && existingPeerID != "" {
-		// Peer already exists
+		// Same pubkey already registered — idempotent.
 		return nil
 	}
 
+	// Dedupe stale embedded peer records for the same (account, cluster).
+	// The proxy generates a fresh WireGuard keypair on every startup
+	// (proxy/internal/roundtrip/netbird.go), so without this sweep the
+	// prior embedded peer would linger forever — holding its CGNAT IP
+	// allocation, polluting other peers' rosters, and (most visibly)
+	// leaving the synth DNS pointing at the dead address. The
+	// (account, cluster) tuple identifies "the embedded peer for this
+	// proxy instance at this cluster"; any record matching that tuple
+	// with a different pubkey is by definition stale and must go.
+	staleIDs, err := m.findStaleEmbeddedProxyPeers(ctx, accountID, cluster, peerKey)
+	if err != nil {
+		return fmt.Errorf("scan for stale embedded proxy peers: %w", err)
+	}
+	if len(staleIDs) > 0 {
+		// userID="" + checkConnected=false: the deletion is initiated
+		// by management itself on behalf of the freshly-registering
+		// proxy, not by an end user; the stale peer may still be
+		// marked Connected from its prior session, but its session is
+		// dead by definition (its key no longer exists).
+		if err := m.DeletePeers(ctx, accountID, staleIDs, "", false); err != nil {
+			return fmt.Errorf("delete stale embedded proxy peers %v: %w", staleIDs, err)
+		}
+	}
+
 	name := fmt.Sprintf("proxy-%s", xid.New().String())
-	peer := &peer.Peer{
+	newPeer := &peer.Peer{
 		Ephemeral: true,
 		ProxyMeta: peer.ProxyMeta{
 			Cluster:  cluster,
@@ -242,10 +266,36 @@ func (m *managerImpl) CreateProxyPeer(ctx context.Context, accountID string, pee
 		},
 	}
 
-	_, _, _, _, err = m.accountManager.AddPeer(ctx, accountID, "", "", peer, true)
+	_, _, _, _, err = m.accountManager.AddPeer(ctx, accountID, "", "", newPeer, true)
 	if err != nil {
 		return fmt.Errorf("failed to create proxy peer: %w", err)
 	}
 
 	return nil
 }
+
+// findStaleEmbeddedProxyPeers returns the peer IDs of embedded proxy peer
+// records in accountID that target the same cluster but carry a different
+// WireGuard pubkey than the freshly-registering one. Used by CreateProxyPeer
+// to garbage-collect stale records left behind when the proxy restarts with a
+// regenerated keypair.
+func (m *managerImpl) findStaleEmbeddedProxyPeers(ctx context.Context, accountID, cluster, newKey string) ([]string, error) {
+	account, err := m.store.GetAccount(ctx, accountID)
+	if err != nil {
+		return nil, err
+	}
+	var stale []string
+	for _, p := range account.Peers {
+		if p == nil || !p.ProxyMeta.Embedded {
+			continue
+		}
+		if p.ProxyMeta.Cluster != cluster {
+			continue
+		}
+		if p.Key == newKey {
+			continue
+		}
+		stale = append(stale, p.ID)
+	}
+	return stale, nil
+}