The tree endpoint has accepted `showHidden=true` since it was written; the
panel hardcoded `showHidden=false`, so dot-prefixed entries were unreachable
from the File Viewer and opening one meant guessing its path.
Adds a `.*` toggle to the panel header. It re-fetches instead of re-rendering
the cached tree (the filtering is server-side), preserves the expanded
directories so toggling does not collapse the tree, and persists per-device to
its own `codeman:fileBrowserShowHidden` key. That key is deliberately not part
of the app-settings object, which `saveAppSettings()` rebuilds from the
settings-modal DOM and would drop it on the next save.
Default is OFF, so an untouched install behaves exactly as before.
Closes#221
Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Aamer Akhter