Rewrite run_local_agent: code-based flow, concurrency guard, remove isApproved

- Replace LLM-driven triage with code-based directory scan and project fetch
- Two-step LLM approach: Step 1 classifies file→project+domains, Step 2 processes with tools
- Add domain descriptions to Step 1 prompt for better extraction accuracy
- Add _running_agents set for per-agent concurrency guard (one running instance per agent)
- Return 409 from route before DB write when agent already running
- Remove is_approved from task_agent create/update tools and system prompt
- Remove is_approved from timeline_agent create/update tools and system prompt

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/agents/timeline_agent.py

@@ -25,7 +25,7 @@ TIMELINE_SYSTEM_PROMPT = (
     "  - For listing, project_id must be a UUID; never pass plain names as project_id\n"
     "  - date is a Unix timestamp in milliseconds; convert human-readable dates\n"
     "  - is_ai_suggested: 1 when proactively proposing a timeline, 0 otherwise\n"
-    "  - is_approved: 0 until the user explicitly confirms; then 1\n"
+    "  - is_ai_suggested: 1 when proactively proposing a timeline, 0 otherwise\n"
     "  - For update_timeline, use -1 for integer fields you do not want to change\n"
     "  - Listing without a project_id returns all timelines across projects\n"
     "  - Always echo the title and formatted date in your confirmation."
@@ -54,14 +54,12 @@ async def create_timeline(
     title: str,
     date: int,
     is_ai_suggested: int = 0,
-    is_approved: int = 0,
 ) -> str:
     """Create a project timeline (milestone).
     project_id: REQUIRED UUID of the parent project
     title: descriptive name for the milestone
     date: Unix timestamp in milliseconds
     is_ai_suggested: 1 if proactively suggested, 0 if user-requested
-    is_approved: 0 until the user confirms
     """
     result = await execute_on_client(
         action="insert",
@@ -71,7 +69,6 @@ async def create_timeline(
             "title": title,
             "date": date,
             "isAiSuggested": is_ai_suggested,
-            "isApproved": is_approved,
         },
     )
     row = result["row"]
@@ -83,20 +80,16 @@ async def update_timeline(
     timeline_id: str,
     title: str = "",
     date: int = -1,
-    is_approved: int = -1,
 ) -> str:
     """Update a timeline. Only pass fields that should change.
     timeline_id: UUID of the timeline (required)
     date: -1 means unchanged; any other value sets the new date (ms timestamp)
-    is_approved: -1 means unchanged; 0 or 1 sets the approval state
     """
     updates: dict[str, Any] = {}
     if title:
         updates["title"] = title
     if date != -1:
         updates["date"] = date
-    if is_approved != -1:
-        updates["isApproved"] = is_approved
     result = await execute_on_client(
         action="update",
         table="timelines",