chore: add a command-line translation check

Mirrors the button on the settings page, for verifying a deployment from
the host before anyone signs in, and for watching the cache work.

Measured against the live service, which settles a question the spec had
guessed at: a short phrase takes between 4.6 and 10.7 seconds, because
the endpoint really does start a Claude Code process. The ten-second
timeout the spec assumed would have failed intermittently on exactly the
kind of message this shop writes. Thirty seconds stands.

Cached answers come back in 3 milliseconds, so the cache is worth
roughly three thousand times its complexity.

Quality checked on real phrasing: times and dates survive unchanged
("Ouverture retardée à 14:00" to "Delayed opening at 14:00 today"),
which is what the prompt asks for and what the screen needs.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_012cSY9pVhZmJUKNN7wf1Myd

package.json

@@ -19,7 +19,8 @@
     "screen:preview": "tsx scripts/preview.ts",
     "brand": "tsx scripts/brand.ts",
     "e2e": "playwright test",
-    "holidays:sync": "tsx scripts/sync-holidays.ts"
+    "holidays:sync": "tsx scripts/sync-holidays.ts",
+    "translate:test": "tsx scripts/test-translation.ts"
   },
   "dependencies": {
     "@fontsource-variable/inter": "^5.3.0",