Frontend review fixes: copy buttons, error toasts, page-reset, notes row, localized gate errors ...

- Extension SHA card and token-modal copy buttons wired to GnCopyButton
  text (was :value — dead button); :label localized
- Create/save/export/reveal/token flows show error toasts instead of
  failing silently; failed create/save keeps the modal and user input
- Query debounce resets secretsPage when the search narrows
- History panel drops the misleading metadata block (show-details=false)
- Notes now visible in the detail panel (between category and tags) when
  the secret carries one; notes inputs widened 140 -> 255 chars
- Biometric gate failure/unavailability messages are i18n slugs
  (bio.*), rendered localized instead of raw English debug strings
- backups table formats size (KB) and CREATED timestamp
- vite dev proxy points at the real backend port 8018
- en/ru/uk dictionaries kept at full parity (223 keys)

Verified visually on 1280x900 and 390x844; console clean.

Co-Authored-By: Claude Code <noreply@anthropic.com>

Implement initial gnexus-creds MVP scaffold