Windows startup hangs when restoring a drive root #118

Summary

marka.md 1.6.1 can hang on startup when the persisted folder session contains a Windows drive root.

Environment

• marka.md 1.6.1
• Windows
• WebView2 local storage under %LOCALAPPDATA%\com.mattenarle.markamd\EBWebView\Default\Local Storage\leveldb

Reproduction

Persist either or both of these values and start the app:

mdview.folders = ["V:\\"]
mdview.lastFolder = "V:\\"

The normal UI path can create this state by opening a drive root as a folder.

Actual behavior

Startup restores V:\ and passes it to the recursive folder watcher. Watching the entire drive recursively blocks startup long enough for Windows to report AppHangB1.

Clearing only one key does not recover the app because folder hydration falls back through the other key.

Expected behavior

• Filesystem roots must not be passed to the recursive folder watcher.
• Existing poisoned sessions must clear both mdview.folders and mdview.lastFolder before persisted React state mounts.
• Selecting a filesystem root should be rejected so the state cannot be recreated.
• Unrelated settings such as mdview.lastFile, theme, titlebar visibility, and recent files must remain unchanged.

A Mermaid file stored in mdview.lastFile was tested independently and opens normally.