ci(i18n): fail on new English-identical translations (#1793)

* ci(i18n): fail on new English-identical translations

The drift check only warned about locale values identical to English, so
untranslated strings kept landing. It now fails on any such value that
tools/i18n/identical-en-baseline.json does not record for that locale and
key. The baseline captures today's 2,015 entries: legitimately identical
values (brand and technical names, language autonyms, PIN) and the
existing debt. An entry only covers the English text it recorded, so
copying reworded English into a locale fails too.

Baseline entries that are no longer identical are reported, not fatal.
`pnpm run i18n:baseline:update` rewrites the baseline deliberately; CI
runs `pnpm run i18n:validate` (node tests, then the check) and never
rewrites it. `--fail-on-identical` remains as a strict audit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

* fix(i18n): keep the baseline intact on failed updates and strict audits

`--update-baseline` now writes nothing while any locale is unreadable or
has missing or extra keys, so an incomplete translation cannot reshape
the baseline. `--fail-on-identical` no longer reads the baseline it
ignores, so a damaged file cannot block a strict audit.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

---------

Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

package.json

@@ -79,6 +79,9 @@
         "serve:website": "nx serve website",
         "build:website": "nx build website",
         "i18n:check": "node tools/i18n/check-drift.mjs",
+        "i18n:test": "node --test tools/i18n/check-drift.test.mjs",
+        "i18n:validate": "pnpm run i18n:test && pnpm run i18n:check",
+        "i18n:baseline:update": "node tools/i18n/check-drift.mjs --update-baseline",
         "perf:initial-bytes": "node tools/performance/measure-initial-bytes.mjs",
         "perf:initial-bytes:check": "node tools/performance/measure-initial-bytes.mjs --summary dist/performance/initial-bytes.summary.json && node tools/performance/check-journey-ratchet.mjs --summary dist/performance/initial-bytes.summary.json --only launch/renderer.initialBytes",
         "perf:journeys": "nx run electron-backend-e2e:journeys",