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/database.py

@@ -0,0 +1,24 @@
+from collections.abc import AsyncGenerator
+
+from sqlalchemy.ext.asyncio import AsyncSession, async_sessionmaker, create_async_engine
+
+from api.config import settings
+
+engine = create_async_engine(
+    settings.database_url,
+    echo=settings.debug,
+    pool_pre_ping=True,
+    pool_size=10,
+    max_overflow=20,
+)
+
+async_session_factory = async_sessionmaker(
+    engine,
+    class_=AsyncSession,
+    expire_on_commit=False,
+)
+
+
+async def get_session() -> AsyncGenerator[AsyncSession, None]:
+    async with async_session_factory() as session:
+        yield session