feat: agent coordination system (workflows, locks, components, messages)

Adds /api/coord/* endpoints for real-time cross-session coordination:
- coord_workflows: named units of work per project
- coord_work_items: tasks within workflows with dependency chains
- coord_session_locks: exclusive resource locks with auto-expiry (TTL)
- coord_component_states: live component state per project (upsert)
- coord_messages: cross-session messaging and broadcasts
- /api/coord/status: cross-project snapshot endpoint

Replaces PROJECT_STATE.md as the coordination layer for Claude sessions.

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

api/routers/coord_work_items.py

@@ -0,0 +1,86 @@
+"""Coordination work items router."""
+
+from uuid import UUID
+
+from fastapi import APIRouter, Depends, Query, status
+from sqlalchemy.orm import Session
+
+from api.database import get_db
+from api.middleware.auth import get_current_user
+from api.schemas.coord_work_item import CoordWorkItemCreate, CoordWorkItemResponse, CoordWorkItemUpdate
+from api.services import coord_work_item_service
+
+router = APIRouter()
+
+
+@router.get("", response_model=dict, status_code=status.HTTP_200_OK)
+def list_work_items(
+    workflow_id: str | None = Query(default=None),
+    project_key: str | None = Query(default=None),
+    status_filter: str | None = Query(default=None),
+    assigned_session: str | None = Query(default=None),
+    skip: int = Query(default=0, ge=0),
+    limit: int = Query(default=100, ge=1, le=1000),
+    db: Session = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """List work items with optional filters."""
+    items, total = coord_work_item_service.get_work_items(
+        db,
+        workflow_id=workflow_id,
+        project_key=project_key,
+        status_filter=status_filter,
+        assigned_session=assigned_session,
+        skip=skip,
+        limit=limit,
+    )
+    return {
+        "total": total,
+        "skip": skip,
+        "limit": limit,
+        "work_items": [CoordWorkItemResponse.model_validate(i) for i in items],
+    }
+
+
+@router.post("", response_model=CoordWorkItemResponse, status_code=status.HTTP_201_CREATED)
+def create_work_item(
+    data: CoordWorkItemCreate,
+    db: Session = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Create a new work item within a workflow."""
+    item = coord_work_item_service.create_work_item(db, data)
+    return CoordWorkItemResponse.model_validate(item)
+
+
+@router.get("/{item_id}", response_model=CoordWorkItemResponse, status_code=status.HTTP_200_OK)
+def get_work_item(
+    item_id: UUID,
+    db: Session = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Get a work item by ID."""
+    item = coord_work_item_service.get_work_item_by_id(db, item_id)
+    return CoordWorkItemResponse.model_validate(item)
+
+
+@router.put("/{item_id}", response_model=CoordWorkItemResponse, status_code=status.HTTP_200_OK)
+def update_work_item(
+    item_id: UUID,
+    data: CoordWorkItemUpdate,
+    db: Session = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Update a work item."""
+    item = coord_work_item_service.update_work_item(db, item_id, data)
+    return CoordWorkItemResponse.model_validate(item)
+
+
+@router.delete("/{item_id}", response_model=dict, status_code=status.HTTP_200_OK)
+def delete_work_item(
+    item_id: UUID,
+    db: Session = Depends(get_db),
+    current_user: dict = Depends(get_current_user),
+):
+    """Delete a work item."""
+    return coord_work_item_service.delete_work_item(db, item_id)