refactor: deduplicate shared code into shared/ module

Move duplicated files from chat + batch-agent into shared/:
- shared/ws_context.py — Redis-based tool call round-trip
- shared/llm.py — LiteLLM factory (get_llm, embed)
- shared/agents/ — 4 domain agents (task, note, project, timeline)

Update all service imports to use shared.* instead of app.*.
Delete 12 duplicated files across both services.

shared/ws_context.py

@@ -0,0 +1,132 @@
+"""WebSocket context — Redis-based tool call round-trip.
+
+Shared by Chat and Batch Agent services.  Publishes tool_call frames to
+Redis ``ws:out:{user_id}`` and awaits the result via BRPOP on
+``tool:result:{call_id}``.
+
+Also provides ``set_client_executor`` / ``clear_client_executor`` no-op
+shims for backward compatibility with agent_runner code that originally
+used a DeviceConnectionManager callback.
+"""
+
+from __future__ import annotations
+
+import json
+import logging
+from contextvars import ContextVar
+from typing import Any, Callable, Coroutine
+from uuid import uuid4
+
+from shared.redis import redis_client, tool_result_key, ws_out_channel
+
+logger = logging.getLogger(__name__)
+
+_TOOL_CALL_TIMEOUT = 30  # seconds — BRPOP timeout
+
+# Per-request user_id context var (set before agent runs)
+_current_user_id: ContextVar[str | None] = ContextVar("_current_user_id", default=None)
+
+# Optional collector for debug
+_tool_result_collector: ContextVar[list[dict] | None] = ContextVar(
+    "_tool_result_collector", default=None
+)
+
+
+def set_current_user(user_id: str) -> None:
+    _current_user_id.set(user_id)
+
+
+def clear_current_user() -> None:
+    _current_user_id.set(None)
+
+
+def set_tool_result_collector(lst: list[dict]) -> None:
+    _tool_result_collector.set(lst)
+
+
+def clear_tool_result_collector() -> None:
+    _tool_result_collector.set(None)
+
+
+# ── Compatibility shims ──────────────────────────────────────────────────
+# agent_runner.py originally called set_client_executor / clear_client_executor
+# with a DeviceConnectionManager callback.  In the microservice world the
+# Redis-based execute_on_client replaces this, so these are no-ops.
+
+def set_client_executor(fn: Callable[[dict], Coroutine[Any, Any, dict]] | None) -> None:
+    """No-op — kept for agent_runner compatibility."""
+
+
+def clear_client_executor() -> None:
+    """No-op — kept for agent_runner compatibility."""
+
+
+async def execute_on_client(
+    action: str,
+    table: str | None = None,
+    data: dict[str, Any] | None = None,
+    filters: dict[str, Any] | None = None,
+    vector: list[float] | None = None,
+    limit: int | None = None,
+) -> dict[str, Any]:
+    """Send a tool_call to Electron via Redis and await the result.
+
+    1. Build tool_call payload
+    2. Publish to ws:out:{user_id} (WS Gateway forwards to Electron)
+    3. BRPOP on tool:result:{call_id} (WS Gateway pushes when Electron replies)
+    4. Return result dict
+
+    Raises RuntimeError if no user_id is set or if the call times out.
+    """
+    user_id = _current_user_id.get()
+    if not user_id:
+        raise RuntimeError(
+            "execute_on_client() called without a user_id — "
+            "set_current_user() must be called first."
+        )
+
+    call_id = str(uuid4())
+    payload: dict[str, Any] = {
+        "type": "tool_call",
+        "id": call_id,
+        "action": action,
+    }
+    if table is not None:
+        payload["table"] = table
+    if data is not None:
+        payload["data"] = data
+    if filters is not None:
+        payload["filters"] = {k: v for k, v in filters.items() if v is not None}
+    if vector is not None:
+        payload["vector"] = vector
+    if limit is not None:
+        payload["limit"] = limit
+
+    # Publish tool_call to WS Gateway → Electron
+    channel = ws_out_channel(user_id)
+    await redis_client.publish(channel, json.dumps(payload))
+
+    # Wait for Electron's tool_result
+    result_key = tool_result_key(call_id)
+    response = await redis_client.brpop(result_key, timeout=_TOOL_CALL_TIMEOUT)
+
+    if response is None:
+        raise RuntimeError(
+            f"Tool call {call_id} timed out after {_TOOL_CALL_TIMEOUT}s — "
+            f"device may be offline or unresponsive."
+        )
+
+    # response is (key, value) tuple
+    _, raw = response
+    result = json.loads(raw)
+
+    # Collect for debug if requested
+    collector = _tool_result_collector.get(None)
+    if collector is not None:
+        collector.append({
+            "action": action,
+            "table": table,
+            "data": result,
+        })
+
+    return result