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/conftest.py

@@ -1,4 +1,4 @@
-"""Shared fixtures for AgenticRAG unit tests."""
+"""Shared fixtures for DocuMente unit tests."""
 
 import pytest
 from unittest.mock import Mock, AsyncMock, MagicMock, patch
@@ -13,7 +13,7 @@ sys.path.insert(0, str(Path(__file__).parent.parent.parent.parent.parent / "src"
 def mock_settings():
     """Create a mock Settings object."""
     settings = Mock()
-    settings.app_name = "AgenticRAG"
+    settings.app_name = "DocuMente"
     settings.app_version = "2.0.0"
     settings.debug = True
     settings.cors_origins = ["http://localhost:3000"]