Ukrainian localization; link-preview meta tags on share pages ...

- uk.json: full Ukrainian translation, uk added to SUPPORTED_LOCALES with
  the shared slavic plural rules and a language option in settings
- /p/<token> and /r/<token> are now served by the API: it injects
  og:title/description/url/image/video + twitter:card into the panel's
  index.html so Telegram and Jira previews show the project or report
  (title, description, creation date, screenshot/video). Caddy proxies
  those paths to the server; the public origin comes from PUBLIC_BASE_URL
  or the request host. Verified end-to-end through the prod stack.

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

Rename the service to BugTrail ...

Bug + trail: the recorded trail of actions leading to the bug.
User-facing rename in the web panel shell, extension manifest/popup/
options, API title, i18n locales and README; Firefox id is now
bugtrail@gnexus.space. Internal @ltt/* package scopes unchanged.

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

Server: FastAPI backend with auth, projects, reports, uploads ...

- FastAPI + SQLAlchemy async + Alembic, PostgreSQL in docker-compose
- Auth: argon2id, cookie sessions (web) + bearer tokens (extension)
- Unguessable share tokens (128-bit) on projects and reports
- Content-addressed file storage with mime sniffing, token-scoped download
- Reports with nested steps; server-side password masking

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