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>

Dockerfile

@@ -0,0 +1,20 @@
+FROM python:3.12-slim
+
+WORKDIR /app
+
+# Install uv for fast dependency installation
+RUN pip install uv --no-cache-dir
+
+# Copy dependency spec first for layer caching
+COPY pyproject.toml .
+RUN uv pip install --system --no-cache .
+
+# Copy source
+COPY src/ ./src/
+
+ENV PYTHONUNBUFFERED=1
+ENV PYTHONPATH=/app
+
+EXPOSE 8000
+
+CMD ["uvicorn", "src.main:app", "--host", "0.0.0.0", "--port", "8000"]