feat: initial alpha scaffold — FastAPI + MCP + pgvector

Implements v0.0.1 of OpenBrain:

- FastAPI REST API (capture, search, recent, stats) with Bearer auth
- MCP server (streamable HTTP at /mcp) exposing all 4 tools
- pgvector schema (vector(1024) for bge-m3)
- asyncpg connection pool with lazy init + graceful close
- Ollama embedding client with fallback (stores thought without vector if Ollama unreachable)
- Woodpecker CI pipeline (lint + kaniko build + push to Gitea registry)
- Portainer/Swarm deployment compose
- Mosaic framework files: AGENTS.md, PRD.md, TASKS.md, scratchpad

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

src/db.py

@@ -0,0 +1,18 @@
+import asyncpg
+from src.config import settings
+
+_pool: asyncpg.Pool | None = None
+
+
+async def get_pool() -> asyncpg.Pool:
+    global _pool
+    if _pool is None:
+        _pool = await asyncpg.create_pool(settings.database_url, min_size=2, max_size=10)
+    return _pool
+
+
+async def close_pool() -> None:
+    global _pool
+    if _pool:
+        await _pool.close()
+        _pool = None