slavina/clean up code

• clean up code
• storage: load storage singleton only when needed
• tool_handlers: use Message class instead of dict
• settings: hardcode the v1 prefix
• api_models: use a more specific default ref
• api_models: use a generic type for the ApiResponse
• api_models: removed not-needed validator
• settings: Use the correct type instead of the base settings one
• tests: add a couple basic tests to all endpoints

Bug: T362070