build(lint): don't fail the build on partial community plurals

A Weblate translation of a <plurals> may not fill every CLDR quantity
form its locale defines — e.g. Arabic's import_reminder_prompt_body_existing
omits the "zero" form — which lint flags fatally as MissingQuantity and
aborts the CI build. The missing form falls back to "other" at runtime, so
this is the same partial-translation case we already accept for
MissingTranslation; downgrade MissingQuantity to informational alongside it.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

app/build.gradle.kts

@@ -113,10 +113,13 @@ android {
     lint {
         // Community translations are expected to be partial — a missing string
         // falls back to the English base at runtime — so don't fail the build on
-        // it. Stale/extra keys (ExtraTranslation) stay fatal; scripts/
+        // it. Likewise a translated <plurals> may not fill every CLDR quantity
+        // form its locale defines (e.g. Arabic needs "zero"); the missing form
+        // falls back to "other" at runtime, so MissingQuantity is informational
+        // too. Stale/extra keys (ExtraTranslation) stay fatal; scripts/
         // check_translations.py guards the same invariants with clearer,
         // translator-facing messages.
-        informational += "MissingTranslation"
+        informational += listOf("MissingTranslation", "MissingQuantity")
     }
 
     testOptions {