feat: moved LLMConfigs from User to SearchSpaces

- RBAC soon??
- Updated various services and routes to handle search space-specific LLM preferences.
- Modified frontend components to pass search space ID for LLM configuration management.
- Removed onboarding page and settings page as part of the refactor.

surfsense_backend/app/agents/podcaster/configuration.py

@@ -17,6 +17,7 @@ class Configuration:
     # and when you invoke the graph
     podcast_title: str
     user_id: str
+    search_space_id: int
 
     @classmethod
     def from_runnable_config(