feat: add lesson export and import functionality

- Implemented `LessonExport` and `LessonImport` actions in the action module.
- Added corresponding command parsing for lesson export and import.
- Created functions to handle lesson export and import in the memory module.
- Updated state management to reflect changes after lesson operations.
- Introduced deferred operations for handling asynchronous tasks in the event loop.
- Enhanced the tool execution context to include graduated checks for file operations.
- Added OAuth support with PKCE for secure authorization flows.
- Implemented a loopback server for handling OAuth redirects.
- Refactored various modules to improve code organization and maintainability.

src/app/state/rest.rs

@@ -120,6 +120,7 @@ impl AppStateRest {
             dir_cache: self.dir_cache.clone(),
             internet_mode: self.settings.internet_mode.clone(),
             origin: Origin::Main,
+            graduated_checks: Vec::new(),
         }
     }
 }