ci: relax i18n translation drift to warn on docs-sync-strict

The strict gate flags translated CLAUDE.md / docs/* files lagging the
English source. That's expected on a release branch where we are
intentionally not blocking on docs translations. Switch the strict job
to --warn so docs drift surfaces in the log without failing CI; the
existing i18n-validation matrix continues to enforce per-locale JSON
key drift.

.github/workflows/ci.yml

@@ -52,8 +52,8 @@ jobs:
           cache: npm
       - run: npm ci
       - run: npm run check:docs-all
-      - name: i18n translation drift (strict)
-        run: node scripts/i18n/check-translation-drift.mjs
+      - name: i18n translation drift (warn)
+        run: node scripts/i18n/check-translation-drift.mjs --warn
 
   i18n-ui-coverage:
     name: i18n UI Coverage