feat(ui): enhance loading spinner and update command configuration

- Increase rotating symbol size to 1.5rem for better visibility
- Remove inline size classes in favor of CSS-based sizing
- Add 'claude' command capability alongside 'claude-code' sidecar
- Remove deprecated externalBin configuration from tauri.conf.json
- Standardize rotating symbol styling across components

This improves the visual feedback for loading states and cleans up
the command execution configuration for better flexibility.

src-tauri/tauri.conf.json

@@ -57,9 +57,6 @@
       "icons/128x128@2x.png",
       "icons/icon.icns",
       "icons/icon.png"
-    ],
-    "externalBin": [
-      "binaries/claude-code"
     ]
   }
 }