[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/server/activity/codes.go

@@ -245,6 +245,37 @@ const (
 	// tunnel. Distinct from UserLoggedInPeer (full interactive login).
 	UserExtendedPeerSession Activity = 125
 
+	// AgentNetworkProviderCreated indicates that a user created an Agent Network provider
+	AgentNetworkProviderCreated Activity = 126
+	// AgentNetworkProviderUpdated indicates that a user updated an Agent Network provider
+	AgentNetworkProviderUpdated Activity = 127
+	// AgentNetworkProviderDeleted indicates that a user deleted an Agent Network provider
+	AgentNetworkProviderDeleted Activity = 128
+
+	// AgentNetworkPolicyCreated indicates that a user created an Agent Network policy
+	AgentNetworkPolicyCreated Activity = 129
+	// AgentNetworkPolicyUpdated indicates that a user updated an Agent Network policy
+	AgentNetworkPolicyUpdated Activity = 130
+	// AgentNetworkPolicyDeleted indicates that a user deleted an Agent Network policy
+	AgentNetworkPolicyDeleted Activity = 131
+
+	// AgentNetworkGuardrailCreated indicates that a user created an Agent Network guardrail
+	AgentNetworkGuardrailCreated Activity = 132
+	// AgentNetworkGuardrailUpdated indicates that a user updated an Agent Network guardrail
+	AgentNetworkGuardrailUpdated Activity = 133
+	// AgentNetworkGuardrailDeleted indicates that a user deleted an Agent Network guardrail
+	AgentNetworkGuardrailDeleted Activity = 134
+
+	// AgentNetworkBudgetRuleCreated indicates that a user created an Agent Network budget rule
+	AgentNetworkBudgetRuleCreated Activity = 135
+	// AgentNetworkBudgetRuleUpdated indicates that a user updated an Agent Network budget rule
+	AgentNetworkBudgetRuleUpdated Activity = 136
+	// AgentNetworkBudgetRuleDeleted indicates that a user deleted an Agent Network budget rule
+	AgentNetworkBudgetRuleDeleted Activity = 137
+
+	// AgentNetworkSettingsUpdated indicates that a user updated Agent Network account settings
+	AgentNetworkSettingsUpdated Activity = 139
+
 	AccountDeleted Activity = 99999
 )
 
@@ -400,6 +431,24 @@ var activityMap = map[Activity]Code{
 
 	UserExtendedPeerSession: {"User extended peer session", "user.peer.session.extend"},
 
+	AgentNetworkProviderCreated: {"Agent Network provider created", "agent_network.provider.create"},
+	AgentNetworkProviderUpdated: {"Agent Network provider updated", "agent_network.provider.update"},
+	AgentNetworkProviderDeleted: {"Agent Network provider deleted", "agent_network.provider.delete"},
+
+	AgentNetworkPolicyCreated: {"Agent Network policy created", "agent_network.policy.create"},
+	AgentNetworkPolicyUpdated: {"Agent Network policy updated", "agent_network.policy.update"},
+	AgentNetworkPolicyDeleted: {"Agent Network policy deleted", "agent_network.policy.delete"},
+
+	AgentNetworkGuardrailCreated: {"Agent Network guardrail created", "agent_network.guardrail.create"},
+	AgentNetworkGuardrailUpdated: {"Agent Network guardrail updated", "agent_network.guardrail.update"},
+	AgentNetworkGuardrailDeleted: {"Agent Network guardrail deleted", "agent_network.guardrail.delete"},
+
+	AgentNetworkBudgetRuleCreated: {"Agent Network budget rule created", "agent_network.budget_rule.create"},
+	AgentNetworkBudgetRuleUpdated: {"Agent Network budget rule updated", "agent_network.budget_rule.update"},
+	AgentNetworkBudgetRuleDeleted: {"Agent Network budget rule deleted", "agent_network.budget_rule.delete"},
+
+	AgentNetworkSettingsUpdated: {"Agent Network settings updated", "agent_network.settings.update"},
+
 	DomainAdded:     {"Domain added", "domain.add"},
 	DomainDeleted:   {"Domain deleted", "domain.delete"},
 	DomainValidated: {"Domain validated", "domain.validate"},