feat: remove room synthesize and mycelium catchup

[juliarvalenti]

Summary

Long-standing intent: the room synthesize + mycelium catchup memory-
synthesis system is gone. The narrower plan compiler
(consensus → plan/tasks.md) replaced it. The synthesis "blob summary of
accumulated memory" pattern is no longer how new agents get briefed —
they read the room directory and the compiled plan directly.

What changed

Backend

• routes/rooms.py: drop POST /synthesize and GET /catchup
• services/async_coordination.py: deleted entirely (run_synthesis,
  check_trigger, _llm_synthesize, _notify_synthesis_complete, structured-
  context builder)
• routes/memory.py: drop _check_async_trigger fan-out after writes
• services/metrics.py: drop record_synthesis + record_synthesis_reuse
• models.py + schemas.py: drop Room.coordination_state,
  Room.trigger_config, Room.last_synthesis_at; drop
  RoomCreate.trigger_config; drop those three fields from RoomRead
• alembic 0017: drop the three columns from rooms
• tests: prune obsolete cases (deleted test_structured_memory.py;
  removed test_synthesize_session_display_404, test_room_with_trigger,
  test_async_room_full_flow, the record_synthesis* tests)

CLI

• commands/room.py: drop room synthesize; drop --trigger flag on
  room create; drop mycelium catchup hint from room clone; drop the
  trigger_config row from the room watch header
• commands/memory.py: drop mycelium catchup (memory_catchup)
• cli.py: drop the top-level synthesize and catchup shortcuts

Frontend

• api.ts: drop fetchCatchup + trigger_config from createRoom
• create-room-dialog.tsx: drop the "Synthesis trigger (memory threshold)"
  input
• memory-panel.tsx: drop catchup state; derive memory/contributor counts
  from the loaded memory list instead
• event-stream.tsx: drop the synthesis_complete event case + style entry
• room-card.tsx: deleted (unused, referenced removed coordination_state)
• room/[name]/page.tsx: drop coordination_state from the Room interface

Generated OpenAPI client

• openapi.json regenerated from the live FastAPI app
• mycelium-cli/src/mycelium_backend_client/ and mycelium-client/
  regenerated via openapi-python-client
• synthesize_room*, catchup_room*, *_trigger_config_type_0 files
  removed; net result includes new task_* models the prior snapshot was
  missing (incidental)

Docs

• README, CLAUDE, docs/demo-script.md, docs/stories.html,
  docs/mycelium-dataflow.html
• mycelium-cli/src/mycelium/docs/{overview, memory, rooms, quickstart, cognitive-engine, troubleshooting, index, plan, architecture, guides/structured-memory, concepts/memory}.md
• docs/generate_docs.py: drop the "synthesize / catchup / watch" CLI
  group entry
• docs/index.html, docs/adapters.html, docs/reference.html
  regenerated

SKILLs + promo

• claude_code + openclaw SKILL.md: strip synthesis trigger flag and
  room synthesize command
• mycelium-promo/index.html: already clean — no refs found

Test plan

• fastapi-backend: pytest tests/ --ignore=tests/test_integration.py → 277 passed
• fastapi-backend: ruff check, ruff format --check, ty check → clean
• mycelium-cli: pytest tests/ → 181 passed
• mycelium-cli: ruff check, ruff format --check, ty check → clean
• mycelium-frontend: pnpm build → clean (5 routes)
• OpenAPI spec contains zero synthesize/catchup/trigger_config/
  coordination_state/last_synthesis_at hits
• Manual: run alembic 0017 against a populated dev DB, verify the
  three columns drop cleanly
• Manual: create a room in the UI, verify the "Synthesis trigger"
  field is gone and creation succeeds