fix(frontend): corrected mesh node field mapping in AgentDrillDown ...

The Target Mesh Node dropdown was incorrectly using 'id', 'name', and 'status' instead of the backend's 'node_id', 'display_name', and 'last_status', causing nodes to appear as '(unknown)'.

fix(llm): eradicate gemini-1.5-flash 404 from production ...

- Implemented substring normalization for Gemini models in config.py
- Forced redirection of 1.5-flash to 2.5-flash in RAG service
- Fixed model name resolution in provider factory to handle suffixed names
- Normalized health checks to use 2.5-flash baseline
- Removed hardcoded 1.5-flash defaults from STT/TTS providers and agent loop

Fix frontend build crash by updating getNodes to getUserAccessibleNodes and restore production service sync