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/capabilities/default.json

@@ -18,6 +18,11 @@
           "name": "claude-code",
           "sidecar": true,
           "args": true
+        },
+        {
+          "name": "claude",
+          "sidecar": false,
+          "args": true
         }
       ]
     },
@@ -28,6 +33,11 @@
           "name": "claude-code",
           "sidecar": true,
           "args": true
+        },
+        {
+          "name": "claude",
+          "sidecar": false,
+          "args": true
         }
       ]
     },