chore: apply cargo fmt before release

- Format code in app_config.rs to comply with rustfmt rules
- Remove extra blank line in config.rs
- Format test code in app_config_load.rs for consistency

src-tauri/tests/app_config_load.rs

@@ -100,6 +100,8 @@ fn load_valid_v2_config_succeeds() {
 
     let loaded = MultiAppConfig::load().expect("v2 should load successfully");
     assert_eq!(loaded.version, 2);
-    assert!(loaded.get_manager(&cc_switch_lib::AppType::Claude).is_some());
+    assert!(loaded
+        .get_manager(&cc_switch_lib::AppType::Claude)
+        .is_some());
     assert!(loaded.get_manager(&cc_switch_lib::AppType::Codex).is_some());
 }