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/check_env.py

@@ -62,7 +62,8 @@ def _parse_ollama_models(raw_output: str) -> list[str]:
 
 sys.path.insert(0, str(Path(__file__).parent.parent))
 try:
-    from config import EMBED_MODEL as CONFIGURED_EMBED, OLLAMA_MODEL as CONFIGURED_LLM
+    from ingestion.config import EMBED_MODEL as CONFIGURED_EMBED
+    from rag.config import OLLAMA_MODEL as CONFIGURED_LLM
 except Exception:
     CONFIGURED_EMBED = None
     CONFIGURED_LLM = None