Add state-hub v0.1 — local-first state service for the Custodian

Implements the first live layer of the Custodian cognitive infrastructure:
PostgreSQL schema, FastAPI REST API, FastMCP stdio server, and Observable
Framework telemetry dashboard.

- state-hub/: full stack (docker-compose, FastAPI, Alembic, MCP server, dashboard)
- 5 DB tables: topics, workstreams, tasks, decisions, progress_events
- 11 MCP tools + 5 resources registered in .mcp.json
- Observable dashboard: Overview, Workstreams, Decisions, Progress pages
- CLAUDE.md: session protocol (get_state_summary / add_progress_event ritual)
- ~/.claude/CLAUDE.md: global cross-project reference to the hub
- scripts/pull_image.py: WSL2 TLS-resilient Docker image downloader

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

api/schemas/task.py

@@ -0,0 +1,51 @@
+import uuid
+from datetime import date, datetime
+
+from pydantic import BaseModel, ConfigDict, model_validator
+
+from api.models.task import TaskPriority, TaskStatus
+
+
+class TaskCreate(BaseModel):
+    workstream_id: uuid.UUID
+    title: str
+    description: str | None = None
+    status: TaskStatus = TaskStatus.todo
+    priority: TaskPriority = TaskPriority.medium
+    assignee: str | None = None
+    due_date: date | None = None
+    blocking_reason: str | None = None
+    parent_task_id: uuid.UUID | None = None
+
+
+class TaskUpdate(BaseModel):
+    title: str | None = None
+    description: str | None = None
+    status: TaskStatus | None = None
+    priority: TaskPriority | None = None
+    assignee: str | None = None
+    due_date: date | None = None
+    blocking_reason: str | None = None
+    parent_task_id: uuid.UUID | None = None
+
+    @model_validator(mode="after")
+    def blocking_reason_required_when_blocked(self) -> "TaskUpdate":
+        if self.status == TaskStatus.blocked and not self.blocking_reason:
+            raise ValueError("blocking_reason is required when status is blocked")
+        return self
+
+
+class TaskRead(BaseModel):
+    model_config = ConfigDict(from_attributes=True)
+    id: uuid.UUID
+    workstream_id: uuid.UUID
+    title: str
+    description: str | None = None
+    status: TaskStatus
+    priority: TaskPriority
+    assignee: str | None = None
+    due_date: date | None = None
+    blocking_reason: str | None = None
+    parent_task_id: uuid.UUID | None = None
+    created_at: datetime
+    updated_at: datetime