feat(dsp): integrate DSPy and /tools/summarize

[haz3141]

Implements Step 4 of AI-Enhanced Dev Lab v3.0

Changes

• ✅ Lab vs app separation preserved (lab/dsp/*, mcp-server/server.py only)
• ✅ No secrets; .env.sample updated with DSPY_MODEL=
• ✅ Tests: lab/tests/test_summarize.py and lab/tests/test_server_health.sh
• ✅ Endpoint works: POST /tools/summarize

Features Added

• DSPy Summarize module with configurable model
• FastAPI MCP server with /tools/summarize endpoint
• Unit tests and health check tests
• Environment configuration template

Version

Tagged as v0.3.0