P1 complete: web front, test suite, CI — acceptance ALL GREEN

Fan-out integration + fixes found by the test/acceptance pass:
- FIX ring-buffer: chunks >= capacity skipped bytes now count into the
  monotonic offset (invariant: stream byte k lives at k % capacity) —
  window order was corrupted on unaligned big chunks
- FIX auth: non-numeric cookie expiry no longer bypasses expiration
- FIX protocol: safe-integer validation on ack.bytes / hello.protocol
- FIX @fastify/websocket v11: websocket route must be registered in an
  encapsulated context after plugin load (handler got REST signature)
- FIX flow-control deadlock found by e2e acceptance: client only ACKs
  on data receipt, so pausing with an unACKed residue in (LOW,
  ACK_EVERY] stalled both sides at 0.9 MB. ACK_EVERY now 64 KiB (<=
  LOW invariant, tested) + trailing debounced ACK in the web client
- Web: Vue 3 + Vite + Pinia + Tailwind 4 + vue-i18n (EN/FR) + xterm 6
  (fit + webgl fallback), multiplexed ws-client with reconnect/backoff
  and resync epochs
- Tests: 100 vitest (protocol fuzz, ring edges, auth, pty-manager flow
  control with mocked pty, REST e2e) ; CI Node 22/24 + pack-smoke
- scripts/acceptance-p1.mjs: real daemon + real WS client — boot,
  login, attach, stdin, 10 MB flood w/ ACK (13.7 MB/1.9s, RSS bounded),
  brutal disconnect + replay resync, kill broadcast, SIGTERM drain

packages/server/src/app.ts

@@ -73,7 +73,11 @@ export function buildApp(config: Config, db: Db, serverVersion: string): AppBund
 
   registerAuthRoutes(app, auth, limiter, serverVersion);
   registerSessionRoutes(app, manager);
-  registerWsGateway(app, manager, serverVersion);
+  // La route websocket doit être déclarée APRÈS le chargement du plugin (contexte
+  // encapsulé) — sinon le handler reçoit la signature REST (request, reply).
+  void app.register(async (scoped) => {
+    registerWsGateway(scoped, manager, serverVersion);
+  });
 
   // SPA buildée embarquée dans le paquet npm (public/) — absente en dev (vite dev sert le front)
   const publicDir = join(dirname(fileURLToPath(import.meta.url)), '..', 'public');