Offline mode with local LLM fallback

[sbharatjoshi]

Summary

Enable offline/air-gapped deployments where Synaptiq uses a local LLM (via Ollama) when cloud providers are unavailable.

Acceptance Criteria

• Automatic fallback to local Ollama when cloud LLM is unavailable
• Graceful degradation of features (some DSL components may not be available)
• Local embedding model for vector search
• Connectivity status indicator in UI