feat(deploy): platform handoff — agent routing, persistence, docs cleanup

Agent routing:
- Remove !agent command and manual agent selection flow
- Registry auto-assigns agent from user_agents mapping (fallback: agents[0])
- provision_workspace_chat and !new both write agent_id to room_meta
- Reconciliation backfills agent_id from registry on cold start
- Fix duplicate agent_id block in auth.py

Deployment stability:
- Add bot-state named volume to persist lambda_matrix.db and matrix_store
- Fix docker-compose.prod.yml duplicate environment: key (was silently losing all Matrix credentials)
- Fix MATRIX_AGENT_REGISTRY_PATH to use absolute container path /app/config/...
- Add bot-state volume declaration to docker-compose.fullstack.yml

Docs and config:
- Rewrite README.md for platform handoff (deploy table, working commands only)
- Rewrite docs/matrix-prototype.md (remove stale commands and mock descriptions)
- Remove !save/!load/!context/!agent from help text and welcome message
- Add !clear, !list, !remove, !yes/!no to help text
- Clean up .env.example (remove Telegram token, internal vars, real URLs)
- Update config/matrix-agents.example.yaml with user_agents section and comments
- Add explanatory comment to Dockerfile for --ignore-requires-python
- Remove silent uv sync fallbacks in Dockerfile

adapter/matrix/handlers/__init__.py

@@ -1,6 +1,5 @@
 from __future__ import annotations
 
-from adapter.matrix.handlers.agent import make_handle_agent
 from adapter.matrix.handlers.chat import (
     handle_list_chats,
     make_handle_archive,
@@ -39,9 +38,7 @@ def register_matrix_handlers(
     prototype_state=None,
     agent_base_url: str = "http://127.0.0.1:8000",
 ) -> None:
-    if store is not None and registry is not None:
-        dispatcher.register(IncomingCommand, "agent", make_handle_agent(store, registry))
-    dispatcher.register(IncomingCommand, "new", make_handle_new_chat(client, store))
+    dispatcher.register(IncomingCommand, "new", make_handle_new_chat(client, store, registry))
     dispatcher.register(IncomingCommand, "chats", handle_list_chats)
     dispatcher.register(IncomingCommand, "rename", make_handle_rename(client, store))
     dispatcher.register(IncomingCommand, "archive", make_handle_archive(client, store))