Remove the old WebDAV/SMB remote storage layer (RemoteStorage, WebDavClient,
SmbClient) and replace it with restic's built-in rclone backend. Unify the
two config cards into a single "Restic remote backup" card with backend
selector (local/WebDAV/SMB). Fix binary execution on Android 10+ via linker
trampoline to bypass W^X restrictions.
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
