fix(dashboard): wire up i18n for the analytics dashboard

[Its-My-Work]

Summary

public/dashboard.html shipped with zero i18n integration — every label, section title, empty-state message, gauge caption and tooltip was a hardcoded English literal, even though index.html, kanban.html and schedule.html all support en/uk/ru/fr/he. A user with the interface language set to Russian (or anything but English) saw the whole Dashboard tab stay in English.

• Give dashboard.html the same TR / t() / applyI18nAttrs() / adoptServerLang() contract as kanban.html and schedule.html: read the persisted lang, adopt the server's /api/config lang like the sibling pages do, and route every user-facing string (nav, card titles, hero stats, gauge captions, empty states, tooltips) through t().
• Month abbreviations and session dates now format via Intl/toLocaleDateString using the active locale instead of a hardcoded 'uk-UA'.
• Extend test/i18n-completeness.test.js to include dashboard.html in the key-parity, placeholder-parity and hardcoded-string scans that already cover kanban.html and schedule.html, so this can't silently regress again.

Test plan

• node test/i18n-completeness.test.js passes with dashboard.html included
• Manually switch the interface language on /dashboard and confirm every label/tooltip/empty-state follows it

🤖 Generated with Claude Code

https://claude.ai/code/session_011E2bJQ2sL9LgEWosjvydTR

[Lexus2016]

Thanks — the dashboard i18n work is good and the test extension is exactly right.

Two things I did before merging, both pushed to your fix/dashboard-i18n branch (maintainer edit; you'll want git fetch && git reset --hard origin/fix/dashboard-i18n locally):

1. Rebased the branch onto main with only the dashboard commit. The PR was carrying 10 commits from your fork's main — Dockerfile (opencode in the image), docker-compose.yml (ports commented out, easypanel external network, CPU/memory caps for your VPS) and a server.js change. The compose changes would break docker compose up for everyone without an easypanel network, so they can't ship here. The /api/browse-dirs default-to-WORKDIR change in server.js looks reasonable on its own — open it as a separate PR if you want it in.
2. One fixup commit: adopt the server language BEFORE the first render. adoptServerLang() ran its /api/config fetch concurrently with loadData(), so when localStorage.lang and the server's lang disagreed (another browser, cleared storage) the hero cards / gauges / tooltips rendered in one language and the static labels flipped to the other a moment later. kanban.html awaits the config first; the dashboard now does the same, and adoptServerLang() refreshes document.title too.

npm test → 80 files, exit 0.