refactor: sposta rag.py, retrieve.py, config.py in cartella rag/

- rag/config.py, rag/rag.py, rag/retrieve.py (spostati da radice)
- rag/__init__.py aggiunto per import come package
- path aggiornati: project_root = Path(__file__).parent.parent
- ollama/check_env.py: import da ingestion.config e rag.config
- ollama/test_ollama.py: import da rag.config

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

ollama/test_ollama.py

@@ -11,7 +11,7 @@ import urllib.request
 from pathlib import Path
 
 sys.path.insert(0, str(Path(__file__).parent.parent))
-import config as _cfg
+from rag import config as _cfg
 
 OLLAMA_URL  = _cfg.OLLAMA_URL
 MODEL       = _cfg.OLLAMA_MODEL