fix(smithery): Use container runtime pattern for config discovery

ADR-016: For container runtime deployment, Smithery does not auto-generate
the .well-known/mcp-config endpoint like it does for Python CLI runtime.

Changes:
- Remove [tool.smithery] from pyproject.toml (not used in container mode)
- Remove smithery_server.py (Python CLI runtime specific)
- Add .well-known/mcp-config endpoint to return JSON Schema config
- Add SmitheryConfigMiddleware to extract config from URL query params
- Use ContextVar to pass session config to tool handlers

The container runtime passes config as URL query parameters to /mcp:
  GET /mcp?nextcloud_url=...&username=...&app_password=...

Tested:
- All 164 unit tests passing
- Docker container builds successfully
- .well-known/mcp-config returns valid JSON Schema
- Health endpoints working

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

Dockerfile.smithery

@@ -41,5 +41,4 @@ EXPOSE 8081
 HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
     CMD uv run python -c "import httpx; httpx.get('http://localhost:${PORT:-8081}/health/live').raise_for_status()"
 
-# Run the Smithery-specific entrypoint
-CMD ["uv", "run", "python", "-m", "nextcloud_mcp_server.smithery_main"]
+CMD ["/app/.venv/bin/smithery-main"]