refactor: rename project from AgenticRAG to DocuMente

## Changes
- Update all references from AgenticRAG to DocuMente
- Update README.md with new project description and structure
- Update LICENSE with new project name
- Update API title and descriptions in main.py
- Update frontend components (Layout, Login, Dashboard, Settings)
- Update static HTML page
- Update all documentation files (prd-v2.md, frontend-plan.md, etc.)
- Update test files with new project name
- Update docker-compose.yml, Dockerfile, requirements.txt

## SEO Benefits
- DocuMente combines 'Documento' and 'Mente' (Italian for Document and Mind)
- Memorable and brandable name
- Reflects the core functionality: AI-powered document intelligence

🎉 Project officially renamed to DocuMente!

tests/unit/test_agentic_rag/test_api/test_chat.py

@@ -44,7 +44,7 @@ class TestChatStream:
         response = client.post("/chat/stream", json={"message": "Hello"})
         content = response.content.decode("utf-8")
 
-        assert "data: Hello from AgenticRAG!" in content
+        assert "data: Hello from DocuMente!" in content
         assert "data: Streaming not fully implemented yet." in content
         assert "data: [DONE]" in content