* fix(app): distinguish changed and deleted files
Successful reads now reconcile transient missing events without letting stale
cached data mask a deletion. File notices expose only actions valid for the
current buffer state.
* fix(app): preserve file state ordering
* fix(app): allow retrying file checks
* fix(app): clear unchanged file conflicts
* fix(app): keep file conflict recovery consistent
Own disk observation and read ordering in one model so stale reads and failed subscriptions cannot produce contradictory actions.
* fix(app): allow retrying file preview errors
Preserve daemon read errors and expose retry for initial and non-editable file loads.
