[falbany]

Summary

Batch of three small frontend issues, each independent of the others:

#139 — LogViewerModal

• Stale-response guard: load() is tagged with a monotonic sequence ref; a slow response carrying a previous filter's results can no longer overwrite newer ones (same epoch pattern as FilePropertiesModal).
• Double fetch on open: the debounced filter effect skips its first run after open — the initial-fetch effect already loaded those filters.
• Shortcut hint: the footer now says "Ctrl + Shift + L toggles this viewer", matching the actual binding (it never opened the file externally).

#140 — BarcodeModal

• Live regeneration is debounced (250 ms) instead of firing one request per keystroke.
• Each generate is tagged; out-of-order responses for older content are dropped instead of leaving a stale image on screen.
• Generate failures now surface in the modal's alert area instead of only console.error (No Silent Failures).

#141 — assorted low-severity fixes

1. ConfigEditorModal: backdrop close fires only when the press and the release both land on the overlay — a text-selection drag starting inside the editor no longer opens the "Discard changes?" dialog mid-selection.
2. Open-log: the missing .catch on openLogFile() now shows an error toast.
3. Verify-hash: when navigator.clipboard.readText() is refused (WKWebView / WebKitGTK), a small manual-entry dialog collects the expected hash instead of failing; the empty-clipboard toast behavior is unchanged.
4. Hidden badge: hard-coded slate classes replaced with theme tokens (was near-invisible in the light theme).
5. revealFile: client response type aligned to the server's {status, message, path} via a shared ActionResponse interface.

Testing

• New LogViewerModal.test.tsx (4 tests): single fetch on open, debounced filter refetch, stale-response dropped, hint text.
• New BarcodeModal.test.tsx (4 tests): debounced single generate, stale response dropped, failure surfaced, empty payload clears image+error.
• Full web suite: 254 passed (16 files). tsc -b clean; dist rebuilt and committed.

Closes #139, closes #140, closes #141