feat(settings): add quick messages management with drag-and-drop sorting

Adds a new "Quick Messages" settings page below Experts for managing reusable title/content snippets, backed by SQLite via SeaORM and exposed through both Tauri commands and the Axum web router. The list supports drag-to-reorder using the same motion/react Reorder pattern as the agent list, with translations provided across all 10 supported locales.

src-tauri/src/commands/mod.rs

@@ -9,6 +9,7 @@ pub mod model_provider;
 #[cfg(feature = "tauri-runtime")]
 pub mod notification;
 pub mod project_boot;
+pub mod quick_messages;
 pub mod system_settings;
 pub mod terminal;
 pub mod version_control;