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

app/schemas.py

@@ -41,41 +41,13 @@ class ChatContext(BaseModel):
     conversation_history: list[dict[str, Any]] = Field(default_factory=list)
 
 
-class PlanAction(BaseModel):
-    type: Literal[
-        "create_record",
-        "update_record",
-        "delete_record",
-        "index_document",
-        "send_notification",
-    ]
-    table: str | None = None
-    data: dict[str, Any] | None = None
-
-
 class ChatRequest(BaseModel):
     message: str
     context: ChatContext = Field(default_factory=ChatContext)
-    execution_mode: Literal["direct", "plan"] = "direct"
 
 
 class ChatResponse(BaseModel):
     response: str
-    actions: list[PlanAction] = Field(default_factory=list)
-
-
-# ── Execution Plans ──────────────────────────────────────────────────
-
-class PlanStep(BaseModel):
-    action: str
-    prompt_template: str | None = None
-    variables: dict[str, Any] | None = None
-    data_from_step: int | None = None
-
-
-class ExecutionPlan(BaseModel):
-    agent: str
-    steps: list[PlanStep] = Field(default_factory=list)
 
 
 # ── Backup ───────────────────────────────────────────────────────────