refactor: replace orchestrator with LangGraph deep-agent supervisors

- Add app/core/deep_agent.py with Home and Floating supervisor graphs
  using LangGraph create_react_agent (hierarchical pattern)
- Strip ChatAgent classes from all 4 agent files, keep @tool functions
- Rewrite output_formatter.py for event-based (token/tool_end/mutations) stream
- Update device_ws.py to use run_home_stream/run_floating_stream
- Rewrite chat.py REST route to use run_home
- Add update_core_memory tool to both supervisors
- Add langgraph>=0.3.0 to requirements.txt
- Remove orchestrator.py, execution_plan.py, agent_registry.py, plans.py
- Remove PlanAction, PlanStep, ExecutionPlan, execution_mode from schemas
- Update all affected tests to match new API
- Remove 6 deprecated test files for deleted modules
- Clean up stale docstrings referencing removed orchestrator

tests/test_ws_unified.py

@@ -45,14 +45,16 @@ def _recv_until_end(ws, max_frames: int = 20) -> list[dict]:
     return frames
 
 
-async def _mock_home_stream(user_id, message, context, reg=None):
-    yield "task_agent", ""
-    yield "task_agent", '{"type": "text", "content": "Hello"}'
+async def _mock_home_stream(user_id, message, context, db_session_factory=None):
+    yield "tool_end", {"name": "task_agent", "result": "Found tasks"}
+    yield "token", "Hello"
+    yield "mutations", []
 
 
-async def _mock_floating_stream(user_id, message, context, reg=None):
-    yield "task_agent", ""
-    yield "task_agent", "Here is a summary"
+async def _mock_floating_stream(user_id, message, context, scope=None, db_session_factory=None):
+    yield "tool_end", {"name": "task_agent", "result": "ok"}
+    yield "token", "Here is a summary"
+    yield "mutations", []
 
 
 # ── tests ─────────────────────────────────────────────────────────────────────
@@ -61,7 +63,7 @@ def test_home_request_produces_stream_frames(client):
     """home_request → stream_start, stream_text+, stream_end."""
     token = make_jwt("power", user_id=USER_ID)
 
-    with patch("app.api.routes.device_ws.orchestrate_v3_stream", side_effect=_mock_home_stream):
+    with patch("app.api.routes.device_ws.run_home_stream", side_effect=_mock_home_stream):
         with client.websocket_connect(f"/api/v1/ws/device?token={token}") as ws:
             ws.send_text(json.dumps({
                 "type": "device_hello", "device_id": "dev-1", "agent_ids": []
@@ -84,7 +86,7 @@ def test_floating_request_produces_domain_frame(client):
     """floating_request → floating_domain first, then stream_text*, stream_end."""
     token = make_jwt("power", user_id=USER_ID)
 
-    with patch("app.api.routes.device_ws.orchestrate_v3_stream", side_effect=_mock_floating_stream):
+    with patch("app.api.routes.device_ws.run_floating_stream", side_effect=_mock_floating_stream):
         with client.websocket_connect(f"/api/v1/ws/device?token={token}") as ws:
             ws.send_text(json.dumps({
                 "type": "device_hello", "device_id": "dev-2", "agent_ids": []
@@ -112,11 +114,12 @@ def test_home_request_request_id_propagated(client):
     token = make_jwt("power", user_id=USER_ID)
     req_id = "my-unique-req-id"
 
-    async def _stream(user_id, message, context, reg=None):
-        yield "note_agent", ""
-        yield "note_agent", '{"type": "text", "content": "ok"}'
+    async def _stream(user_id, message, context, db_session_factory=None):
+        yield "tool_end", {"name": "note_agent", "result": "ok"}
+        yield "token", "ok"
+        yield "mutations", []
 
-    with patch("app.api.routes.device_ws.orchestrate_v3_stream", side_effect=_stream):
+    with patch("app.api.routes.device_ws.run_home_stream", side_effect=_stream):
         with client.websocket_connect(f"/api/v1/ws/device?token={token}") as ws:
             ws.send_text(json.dumps({
                 "type": "device_hello", "device_id": "dev-3", "agent_ids": []