feat(api): integrate screenshot commands and link detection

- Add captureUrlScreenshot() API endpoint
- Add cleanupScreenshotTempFiles() for maintenance
- Register screenshot commands in Tauri backend
- Update command module exports

src-tauri/src/commands/mod.rs

@@ -2,4 +2,5 @@ pub mod claude;
 pub mod agents;
 pub mod sandbox;
 pub mod usage;
-pub mod mcp; 
+pub mod mcp;
+pub mod screenshot;