[BeSovereign]

Refs #626

Added a framework-free i18n layer (public/js/i18n.js, per-module catalogues in public/js/messages/, t() with plurals) with Deutsch (Du) and English for index.html, the app.js shell/settings/toasts and the event dialog; the language is the user's new preference, else navigator.languages, else Deutsch (Du) (fallback noted in CONCEPTS.md), and switching re-renders without reload. This round: the #166 reminder e2e test, which runs in an en-US browser and now gets English per CONCEPTS, pins the German setting to keep checking that a German screen shows the 24-hour clock, and the #626 spec resets the language preference after each test.

Driver gates (measured, not claimed)

• Suites: lint: 1 passed, 0 failed | node: 2018 passed, 0 failed | python: 194 passed, 0 failed | e2e: 349 passed, 0 failed
• Red/green check on declared tests: e2e/issue626_i18n.spec.js, e2e/calendar.spec.js, server/test/issue626_language_preference.test.js, server/test/issue108_search_kanban_empty_state.test.js, server/test/issue215_public_link_unsequenced_writers.test.js, server/test/issue220_unsequenced_calendar_navigation.test.js, server/test/issue226_failed_event_load_toolbar_sync.test.js, server/test/issue498_task_view_preference.test.js, server/test/issue509_secondary_timezone.test.js, server/test/issue517_week_numbers_preference.test.js, server/test/readonly_event_click_popover.test.js, server/test/status_bar_view_counts.test.js

red/green output

RED without the change:
───────────

  5 failed
    [chromium] › e2e/issue626_i18n.spec.js:52:1 › Issue #626 — switching the language re-renders the shell and the event dialog without reload 
    [chromium] › e2e/issue626_i18n.spec.js:100:3 › Issue #626 — an English browser › Issue #626 — without a setting an English browser gets English 
    [chromium] › e2e/issue626_i18n.spec.js:109:3 › Issue #626 — a browser in a language the app does not speak › Issue #626 — without a setting a French browser gets Deutsch (Du) 
    [chromium] › e2e/issue626_i18n.spec.js:114:3 › Issue #626 — a browser in a language the app does not speak › Issue #626 — the setting wins over the browser 
    [chromium] › e2e/issue626_i18n.spec.js:122:1 › Issue #626 — both catalogues hold the same keys, placeholders and plurals; t() fills them 


GREEN with the change:
s:52:1 › Issue #626 — switching the language re-renders the shell and the event dialog without reload (2.8s)
  ✓  2 [chromium] › e2e/issue626_i18n.spec.js:100:3 › Issue #626 — an English browser › Issue #626 — without a setting an English browser gets English (488ms)
  ✓  3 [chromium] › e2e/issue626_i18n.spec.js:109:3 › Issue #626 — a browser in a language the app does not speak › Issue #626 — without a setting a French browser gets Deutsch (Du) (455ms)
  ✓  4 [chromium] › e2e/issue626_i18n.spec.js:114:3 › Issue #626 — a browser in a language the app does not speak › Issue #626 — the setting wins over the browser (499ms)
  ✓  5 [chromium] › e2e/issue626_i18n.spec.js:122:1 › Issue #626 — both catalogues hold the same keys, placeholders and plurals; t() fills them (439ms)

  5 passed (7.6s)

🤖 Generated with Claude Code

[BeSovereign]

Security review (claude-fable-5-1): no blocking finding. Language preference allow-listed on route and by DB CHECK, test has teeth (400 + unchanged state). All t() results with user params are escaped before innerHTML or set via textContent; catalogues hold no markup; translateDom only touches static data-i18n attributes. Suggest a test asserting catalogue strings contain no '<' to protect the escape-at-call-site convention.