fix(security): deliver the hook secret to hooks + isolate its rate-limit bucket

Review fixes for COD-54:

- Generated hook curl commands now present X-Codeman-Hook-Secret, read from
  the secret file AT EXECUTION TIME via $CODEMAN_HOOK_SECRET_FILE (exported
  into every managed session's env by tmux buildEnvExports / the direct-PTY
  env builders). Without this, every local hook 401'd the moment a managed
  tunnel came up — the enforcement existed but nothing presented the secret.
  Path-not-value keeps the secret off command lines and out of config files,
  and running sessions pick up a newly generated secret with no respawn;
  server.start() ensures the file exists up front.

- Hook-secret failures now count into a DEDICATED per-IP bucket
  (hookSecretFailures) instead of the shared authFailures map. Legacy
  (pre-secret) hook configs fire constantly from 127.0.0.1; counting their
  401s against the shared bucket would 429 every cookie-less loopback
  request — locking out the Basic-Auth login path (and, through a tunnel,
  every client, since tunneled traffic also arrives as 127.0.0.1).

- docs/security-architecture.md: secret-gated hook exemption, dedicated
  bucket, COD-55 refusal, and the residual caveat for EXTERNAL loopback
  proxies (user-run cloudflared / tailscale serve), which the
  managed-tunnel probe cannot see.

- test/cod54-hook-event-auth.test.ts: +3 tests — login path unaffected
  after hook-bucket exhaustion; generated hooks reference the header +
  $CODEMAN_HOOK_SECRET_FILE without embedding the value; env builders
  export the path only.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

src/web/server.ts

@@ -41,6 +41,7 @@ import fs from 'node:fs/promises';
 import { execSync } from 'node:child_process';
 import { hostname as getHostname } from 'node:os';
 import { dataPath } from '../config/instance.js';
+import { getHookSecret } from '../config/hook-secret.js';
 import { EventEmitter } from 'node:events';
 import { Session, isExternalCliMode, type BackgroundTask } from '../session.js';
 import type { ClaudeMode, SessionState } from '../types.js';
@@ -253,6 +254,7 @@ export class WebServer extends EventEmitter {
   private authSessions: StaleExpirationMap<string, import('./ports/auth-port.js').AuthSessionRecord> | null = null;
   private authFailures: StaleExpirationMap<string, number> | null = null;
   private qrAuthFailures: StaleExpirationMap<string, number> | null = null;
+  private hookSecretFailures: StaleExpirationMap<string, number> | null = null;
   private pushStore: PushSubscriptionStore = new PushSubscriptionStore();
   private teamWatcher: TeamWatcher = new TeamWatcher();
   private _orchestratorLoop: import('../orchestrator-loop.js').OrchestratorLoop | null = null;
@@ -608,6 +610,7 @@ export class WebServer extends EventEmitter {
       this.authSessions = authState.authSessions;
       this.authFailures = authState.authFailures;
       this.qrAuthFailures = authState.qrAuthFailures;
+      this.hookSecretFailures = authState.hookSecretFailures;
     }
 
     // WebSocket support (terminal I/O — low-latency bidirectional channel)
@@ -1816,6 +1819,10 @@ export class WebServer extends EventEmitter {
       this.host === '0.0.0.0' || this.host === 'localhost' || this.host === '::1' ? '127.0.0.1' : this.host;
     process.env.CODEMAN_API_URL = `${protocol}://${apiHost}:${this.port}`;
 
+    // Ensure the COD-54 hook secret exists on disk before any session exports
+    // $CODEMAN_HOOK_SECRET_FILE — hook curls cat that path at execution time.
+    getHookSecret();
+
     // Start scheduled runs cleanup timer
     this.cleanup.setInterval(
       () => {
@@ -2292,6 +2299,10 @@ export class WebServer extends EventEmitter {
       this.qrAuthFailures.dispose();
       this.qrAuthFailures = null;
     }
+    if (this.hookSecretFailures) {
+      this.hookSecretFailures.dispose();
+      this.hookSecretFailures = null;
+    }
     this.activePlanOrchestrators.clear();
     this.cleaningUp.clear();