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_workflow.py

@@ -0,0 +1,42 @@
+"""Pydantic schemas for CoordWorkflow."""
+
+from datetime import datetime
+from typing import Optional
+from uuid import UUID
+
+from pydantic import BaseModel, Field
+
+
+class CoordWorkflowCreate(BaseModel):
+    """Input schema for creating a workflow."""
+
+    project_key: str = Field(..., description="Project namespace slug", max_length=200)
+    name: str = Field(..., description="Short workflow identifier", max_length=200)
+    description: Optional[str] = Field(None, description="Freeform description, markdown ok")
+    status: str = Field("planning", description="Status: planning, active, blocked, completed, cancelled")
+    created_by: str = Field(..., description="Creating session identifier", max_length=200)
+
+
+class CoordWorkflowUpdate(BaseModel):
+    """Input schema for updating a workflow. All fields optional."""
+
+    name: Optional[str] = Field(None, max_length=200)
+    description: Optional[str] = None
+    status: Optional[str] = Field(None, description="Status: planning, active, blocked, completed, cancelled")
+    completed_at: Optional[datetime] = None
+
+
+class CoordWorkflowResponse(BaseModel):
+    """Output schema for a workflow."""
+
+    id: UUID
+    project_key: str
+    name: str
+    description: Optional[str]
+    status: str
+    created_by: str
+    completed_at: Optional[datetime]
+    created_at: datetime
+    updated_at: datetime
+
+    model_config = {"from_attributes": True}