Phase1 skeleton: replace demo main.py with src.server contract

- Overlay ModelHub XC Phase1 (health/status, STRATEGY_ID gate, dry-run)
- Dockerfile CMD -> python -m src.server; FROM stays platform TCR base
- Remove demo main.py and requirements.txt (stdlib only)
- Add tests/, scripts/, docs/, Makefile, config/examples (no secrets)

.dockerignore

@@ -1,4 +1,21 @@
 .git
-__pycache__/
-*.pyc
-.pytest_cache/
+.gitignore
+.venv
+venv
+__pycache__
+*.py[cod]
+*$py.class
+.pytest_cache
+.mypy_cache
+reports/*
+!reports/.gitkeep
+docs
+tests
+scripts
+config
+*.md
+!README.md
+.env
+.env.*
+*.log
+.DS_Store