fix(ui): harden settings focus and semantics

slang.yaml

@@ -2,8 +2,8 @@ input_directory: lib/i18n
 input_file_pattern: .i18n.json
 output_directory: lib/i18n
 timestamp: false
-# Fall back to base (en) for any key missing in a non-base locale.
-# Without this, every locale would need every key declared up-front and
-# the generator would emit `class is missing implementations for…`
-# errors when a new English string lands.
-fallback_strategy: base_locale
+# Fall back to base (en) when a non-base key is missing or still has the
+# translation cleanup placeholder (`""`). Without this, every locale would
+# need every key translated up-front and empty placeholders would render
+# without meaningful text.
+fallback_strategy: base_locale_empty_string