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/schemas/coord_session_lock.py

@@ -0,0 +1,41 @@
+"""Pydantic schemas for CoordSessionLock."""
+
+from datetime import datetime
+from typing import Optional
+from uuid import UUID
+
+from pydantic import BaseModel, Field
+
+
+class CoordSessionLockCreate(BaseModel):
+    """Input schema for claiming a lock."""
+
+    project_key: str = Field(..., description="Project namespace", max_length=200)
+    session_id: str = Field(..., description="Session claiming the lock", max_length=200)
+    resource: str = Field(..., description="Resource path being locked, e.g. 'server/src/'", max_length=500)
+    description: Optional[str] = Field(None, description="Why this lock is needed")
+    ttl_hours: float = Field(2.0, description="Lock lifetime in hours; 0 = no expiry", ge=0)
+
+
+class CoordSessionLockUpdate(BaseModel):
+    """Input schema for updating a lock (rarely needed directly)."""
+
+    description: Optional[str] = None
+    expires_at: Optional[datetime] = None
+
+
+class CoordSessionLockResponse(BaseModel):
+    """Output schema for a lock."""
+
+    id: UUID
+    project_key: str
+    session_id: str
+    resource: str
+    description: Optional[str]
+    acquired_at: datetime
+    expires_at: Optional[datetime]
+    released_at: Optional[datetime]
+    created_at: datetime
+    updated_at: datetime
+
+    model_config = {"from_attributes": True}