ci: enforce flutter/biome format checks and fix front lint violations

devfront/src/components/common/LanguageSelector.tsx

@@ -44,12 +44,8 @@ function LanguageSelector() {
       className="rounded-full border border-border bg-transparent px-3 py-2 text-sm text-muted-foreground transition hover:bg-muted/20"
       aria-label={t("ui.common.language", "언어")}
     >
-      <option value="ko">
-        {t("ui.common.language_ko", "한국어")}
-      </option>
-      <option value="en">
-        {t("ui.common.language_en", "English")}
-      </option>
+      <option value="ko">{t("ui.common.language_ko", "한국어")}</option>
+      <option value="en">{t("ui.common.language_en", "English")}</option>
     </select>
   );
 }