refactor: reduce logging of SQLite pragmas and enhance model provider type safety (#5235)

* feat: add ModelProvidersDict TypedDict and update MODEL_PROVIDERS_DICT type annotation

- Introduced ModelProvidersDict as a TypedDict to define the structure for model provider configurations.
- Updated MODEL_PROVIDERS_DICT to use the new TypedDict for improved type safety and clarity.
- Enhanced code readability and maintainability by specifying input types for model providers.

* fix: prevent duplicate logging of SQLite pragmas in DatabaseService

- Added a flag to track whether SQLite pragmas have been logged to avoid redundant log entries.
- Improved logging efficiency by ensuring that the debug message for setting pragmas is only logged once per session.