fix: resolve model switch UI freeze on edge cases

[NSIETeam]

Bug Fix: Model switch UI freeze on edge cases

Problem

Users experience the model selector UI permanently showing "Switching..." in two scenarios:

1. switchModel() throws an exception: The catch block sends sendModelResponse({success:false}) but does NOT send model_switch_complete. The frontend's isModelSwitching flag is only cleared when model_switch_complete is received, so the UI gets stuck.

2. geminiClient is null: When geminiClient is unavailable but config.setModel exists, the model is switched successfully but no model_switch_complete event is emitted, leaving the frontend out of sync.

Fix

Fix 1 (extension.ts catch block): Added sendModelSwitchComplete() call in the catch block of onSetCurrentModel handler, so the frontend clears isModelSwitching even on failure.

Fix 2 (extension.ts config.setModel path): Added sendModelSwitchComplete() call after config.setModel(), ensuring the frontend is notified when the model is switched via the config fallback path.

Files Changed

• packages/vscode-ui-plugin/src/extension.ts (+6 lines)

Testing

• Code review confirms both code paths now emit model_switch_complete
• Manual test: trigger switchModel failure, verify UI recovers
• Manual test: model switch with null geminiClient, verify UI updates