closes #1823

<!-- This is an auto-generated description by cubic. -->
---
## Summary by cubic
Blocks invalid characters in app folder paths during rename and shows
cleaner error messages in App Details. Prevents OS rename failures and
removes confusing IPC prefixes from errors.

- **Bug Fixes**
- Validate new appPath on rename; reject < > : " | ? * / \ and control
characters when the path changes, with a clear error message.
- Replace alert() with showError() and strip the IPC wrapper text for
user-friendly errors.

<sup>Written for commit 14b3c0978c1da3b97ca6d33e67684c7ff872ab0a.
Summary will update automatically on new commits.</sup>

<!-- End of auto-generated description by cubic. -->