v1.13.11-a: WS frame schemas + frontend receive validation

First half of the WebSocket-frame-typing batch (split per recon — total
scope was ~535 LoC, larger than the roadmap's ~300 estimate, so the
server-side publish-site conversion lands separately in v1.13.11-b).

Phase A scope:

(1) apps/server/src/types/ws-frames.ts (NEW) — Zod schemas for all 27
wire-format WS frame types. Discriminated union (WsFrameSchema) plus
KNOWN_FRAME_TYPES const for diagnostic lookup. UUIDs are z.string().
uuid(); model-emitted tool_call_id stays z.string().min(1) since OpenAI-
compatible APIs emit "call_<random>" not UUID. Per-kind payload narrowing
(tool args, message_parts payloads) intentionally stays z.unknown() —
frame-level drift detection is the goal; deep payload validation is
follow-up work.

(2) apps/web/src/api/ws-frames.ts (NEW) — byte-identical mirror of the
authoritative server file. No path alias from web→server in the existing
tsconfig setup; sync-by-hand was chosen over a new packages/shared/ dir.
A ws-frames.test.ts test asserts the two files match.

(3) apps/server/src/services/broker.ts — adds publishFrame() and
publishUserFrame() methods to the Broker interface. Both validate via
WsFrameSchema and fail-closed: log + drop on invalid. createBroker now
accepts an optional FastifyBaseLogger so validation failures land in
the pino stream (with console.error fallback for unit tests). The
existing publish() / publishUser() raw methods stay legal — they get
converted to the typed variants in v1.13.11-b.

(4) apps/web/src/hooks/useSessionStream.ts + useUserEvents.ts — wrap
ws.onmessage with WsFrameSchema.safeParse. Fail-closed: invalid frames
log + return without dispatching. Hand-maintained WsFrame and
SessionEvent types stay in place; one cast bridges Zod-typed → narrowed
shape (Zod uses OpaqueObject for nested Message[] / WorkspacePane[] etc.,
which are dev-time-narrowed via the existing hand-maintained types).

(5) apps/web/package.json — adds zod ^3.23.8 as a direct dep. Was a
transitive dep via ai-sdk / postgres; promotion makes the import legal.

(6) Tests: 15 new in ws-frames.test.ts covering happy-path per major
frame type, drift-catchers (unknown type, invalid enum, non-UUID, negative
tokens), parts-authoritative read variants, the mirror-file diff check,
and four broker fail-closed scenarios. 219/219 server tests pass (was
204; +15 new).

Two recon corrections to the dispatch brief, both flagged before
implementation:

- No 'parts_appended' frame exists. The brief assumed one; the codebase
  reads parts via the messages_with_parts view after message_complete
  triggers a refetch. MessagePartSchema is therefore unused this batch.
- No 'tool_running' frame exists. The brief listed it as standalone; it
  is in fact a 'chat_status' variant ({ status: 'tool_running' }), already
  covered by ChatStatusFrame.

Smoke: clean container boot, no validation errors in the server log. Real
production frames pass validation (the schemas were derived from the
existing hand-maintained types in api/types.ts and sessionEvents.ts).

v1.13.11-b will follow immediately: convert all ~85 raw broker.publish /
ctx.publish call sites across 11 server files to publishFrame /
publishUserFrame. Mechanical edit; the wiring done here means the diff
in -b is just the call-site swaps.

~310 LoC across 9 files (4 new + 5 modified).

pnpm-lock.yaml

@@ -157,6 +157,9 @@ importers:
       tw-animate-css:
         specifier: ^1.4.0
         version: 1.4.0
+      zod:
+        specifier: ^3.23.8
+        version: 3.25.76
     devDependencies:
       '@tailwindcss/postcss':
         specifier: ^4.3.0