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>

.env.example

@@ -0,0 +1,12 @@
+# Database — update host/credentials for your deployment
+DATABASE_URL=postgresql://openbrain:changeme@brain-db:5432/openbrain
+
+# Auth — generate a strong random key: openssl rand -hex 32
+API_KEY=your-secret-key-here
+
+# Ollama — point at your Ollama instance
+OLLAMA_URL=http://your-ollama-host:11434
+OLLAMA_EMBEDDING_MODEL=bge-m3:latest
+
+# Service
+LOG_LEVEL=info