docs: implementation plan (TTY precedents folded in); task decomposition (17 tasks)

Plan updated with the alknet-tty findings: the drainer pattern
(single ordered writer) makes outbound chunk-boundary parsing sound;
TestStdinSink's try_send→Full→Pending is the inbound backpressure
precedent; OQ-01(a) now cites the reference.

Task graph (taskgraph-validated, 17 tasks, 6 generations, no cycles):
- tasks/server/: core-types, auth, healthz-decoy, adapter
- tasks/gateway/: dispatch, routes, publish
- tasks/websocket/: byte-adapter (research POC), upgrade-session, overlay-ops
- tasks/adapters/: from-openapi, from-jsonschema, to-openapi, from-wss, mcp
- tasks/client/: http-host
- tasks/infra/: integration-suite (phase 4)

Critical path runs through server core → adapter → WS session →
overlay tests → integration suite. High-risk tasks are the three WS
tasks, de-risked by the ws-byte-adapter POC blocking upgrade-session.

docs/architecture/open-questions.md

@@ -20,8 +20,10 @@ with their resolutions; new alkhttp OQs start at OQ-01.
   8-byte header + payload); the mux writes chunks as contiguous byte
   sequences. A WebSocket is message-oriented. The adapter's contract
   needs nailing down before implementation:
-  (a) inbound buffer bound (bounded channel between the WS read task
-  and the `AsyncRead` half — what bound, what policy on overflow);
+  (a) inbound buffer bound (the alknet-tty precedent — bounded mpsc
+  with `try_send` → `Full` → `Pending` backpressure, and the single-
+  drainer ordered-write pattern from `pump_session` — is the working
+  reference; bound value to lock during implementation);
   (b) write-side chunk boundary parsing (verified against alkcall
   source: the mux emits one mpsc payload per chunk, but a logical
   write above the mux — e.g. channel 0's `write_frame`, which issues