revert: restore app/appType param compatibility and revert segmented-thumb pointer-events change

- Restore backend commands to accept app_type/app/appType with priority app_type
- Frontend invoke() now passes both { app_type, app } again
- Revert CSS change that set pointer-events: none on segmented-thumb
- Keep minor fix: open_config_folder signature uses handle + respects both names

Note: warnings for non_snake_case (appType) are expected for compatibility.

src/App.css

@@ -50,7 +50,9 @@
   background: var(--seg-thumb);
   border-radius: 999px;
   box-shadow: 0 4px 10px rgba(0, 0, 0, 0.15);
-  transition: transform 220ms ease, width 220ms ease;
+  transition:
+    transform 220ms ease,
+    width 220ms ease;
   will-change: transform;
 }