v0.0.9: Restructure Vault validation fix

Fixed

• Reject rename when target folder already exists. Previously, if the AI proposed renaming foo bar to foo-bar and foo-bar already existed with content, the OS rejected the operation with ENOTEMPTY mid-flight. The validator now catches this before any I/O and tells the user to re-run (the AI will then propose a merge instead).
• Clearer error when no operations were applied. First-op failures now say "No operations applied before error: …" instead of the misleading "0 renames, 0 merges, 0 moves before error: …".

Changed

• AI prompt now includes an explicit rule: "Use a 'merge' operation, NOT 'rename', when the target folder already exists."

Install

```sh
curl -L -o ai-notes-0.0.9.vsix https://github.com/alexaytov/vscode-ai-notetaking/releases/download/0.0.9/ai-notes-0.0.9.vsix
code --install-extension ai-notes-0.0.9.vsix
```