Prevent setup from overwriting malformed JSON configuration files

[Minh Vu (fallintoplace)]

Summary

• stop configuration when an existing JSON file cannot be parsed
• show an error with an Open Config action
• preserve the existing file byte-for-byte and skip skill installation
• document the data-safety behavior

Testing

• npm run check-types
• npm run lint
• npm test (97 passing)

[Oz Zafar (ozzafar)]

Thanks for the fix. I updated the branch with current main and added explicit recovery guidance to the error popup: after correcting the malformed JSON, users are directed to run DebugMCP: Show Agent Selection Popup from the Command Palette to retry setup.

The existing malformed file remains byte-for-byte unchanged, setup reports failure instead of overwriting it, and skill installation only proceeds after configuration succeeds.