refactor(i18n): harden key checker per review

- Validate static t() keys even under a dynamic prefix (dynamic prefixes now
  only affect the unused calc, not missing) — Copilot
- Strip JS/TS/JSX comments before scanning so keys in comments aren't counted
  as usage — CodeRabbit
- Run i18n:check as part of \un run test\ so local mirrors CI — CodeRabbit
- Fix stale 'all locale files' comment (fixer is source-only) — Copilot

package.json

@@ -24,7 +24,7 @@
     "doctor": "expo-doctor",
     "i18n:check": "bun scripts/check-i18n-keys.mjs",
     "i18n:fix-unused": "bun scripts/check-i18n-keys.mjs --fix-unused",
-    "test": "bun run typecheck && bun run lint && bun run format && bun run doctor",
+    "test": "bun run typecheck && bun run lint && bun run format && bun run i18n:check && bun run doctor",
     "postinstall": "patch-package"
   },
   "dependencies": {