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/key_input.rs

@@ -0,0 +1,6 @@
+use crate::app::state::rest::AppStateRest;
+
+pub fn handle_key_text(state: &mut AppStateRest, text: String) {
+    state.input.buffer = text;
+    state.dirty = true;
+}