[release] v3.9.0 - Conversation timestamps, RAG improvements, Qdrant 1.16

[byerlikaya]

🚀 SmartRAG Pull Request

📝 Description

Release preparation for v3.9.0: conversation timestamps and sources, major RAG search improvements, duplicate upload prevention, Whisper native bootstrap, MCP on-demand connection, and Qdrant.Client 1.16.1 compatibility.

🔗 Related Issue

N/A - Release preparation

🔄 Type of Change

Please mark the relevant options:

• 🐛 Bug fix (non-breaking change which fixes an issue)
• ✨ New feature (non-breaking change which adds functionality)
• 💥 Breaking change (fix or feature that would cause existing functionality to not work as expected)
• 📚 Documentation update
• 🧪 Test improvements
• 🔧 Code refactoring
• 🚀 Release preparation

🧪 Testing

Please describe the tests that you ran to verify your changes:

• Unit tests pass
• Integration tests pass
• Manual testing completed
• SmartRAG.Demo runs without errors
• Build succeeds with 0 errors, 0 warnings

📋 Checklist

• My code follows the SmartRAG style guidelines
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (EN + TR)
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• LoggerMessage definitions are correct (no parameter mismatches)
• EventId assignments are unique (no conflicts)
• Code is generic and provider-agnostic (no hardcoded domain-specific names)
• All public APIs have XML documentation

🚨 Critical Rules Compliance

• Generic Code: No hardcoded table/database/column names
• Error Fixing: Only fixed the reported error, no refactoring
• Build Quality: 0 errors, 0 warnings, 0 messages
• Language: All code elements in English only
• SOLID/DRY: Principles followed

📸 Screenshots (if applicable)

N/A

📋 Additional Context

• Version: 3.9.0
• Breaking Changes: IStorageFactory.GetCurrentRepository(IServiceProvider), IConversationRepository new methods, IQdrantCacheManager removed
• Migration Guide: Added in docs/en/changelog/migration-guides.md and docs/tr/changelog/migration-guides.md

🔄 Migration Guide (if breaking changes)

See docs/changelog/migration-guides.md for v3.8.x → v3.9.0 migration:

IStorageFactory:

// Before (v3.8.x)
var repository = _storageFactory.GetCurrentRepository();

// After (v3.9.0)
var repository = _storageFactory.GetCurrentRepository(_serviceProvider);

IConversationRepository (custom implementations): Add AppendSourcesForTurnAsync, GetSourcesForSessionAsync, GetAllSessionIdsAsync.

IQdrantCacheManager: Removed - remove any references.

📊 Performance Impact

• No performance impact
• Performance improvement
• Performance regression (explain below)

🔒 Security Considerations

• No security implications
• Security improvement
• Security concern (explain below)