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/mode/mod.rs

@@ -1,22 +1,40 @@
 use serde::{Deserialize, Serialize};
 
+#[expect(dead_code)]
 pub mod agents;
+#[expect(dead_code)]
 pub mod bash;
+#[expect(dead_code)]
 pub mod editor;
+#[expect(dead_code)]
 pub mod effort;
+#[expect(dead_code)]
 pub mod help;
+#[expect(dead_code)]
 pub mod key_input;
+#[expect(dead_code)]
 pub mod loading;
+#[expect(dead_code)]
 pub mod mcp;
+#[expect(dead_code)]
 pub mod onboard;
+#[expect(dead_code)]
 pub mod onboard_provider;
+#[expect(dead_code)]
 pub mod picker;
+#[expect(dead_code)]
 pub mod quit_confirm;
+#[expect(dead_code)]
 pub mod rewind;
+#[expect(dead_code)]
 pub mod security;
+#[expect(dead_code)]
 pub mod session_hub;
+#[expect(dead_code)]
 pub mod settings;
+#[expect(dead_code)]
 pub mod todo;
+#[expect(dead_code)]
 pub mod workflow;
 
 #[derive(Debug, Clone, Copy, PartialEq, Eq, Serialize, Deserialize)]