feat(web): add floating feedback FAB on homepage linking to Tally form

Collect beta user feedback via Tally.so — fixed-position button in the
bottom-right corner opens the form in a new tab. Ember-orange default,
clay-dark on hover, i18n labels for zh-CN / en / ja.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

app/[locale]/page.tsx

@@ -2155,6 +2155,18 @@ export default function HomePage() {
         </div>
       </footer>
 
+      {/* ================== 反馈悬浮按钮 ================== */}
+      <a
+        href="https://tally.so/r/VLqO1M"
+        target="_blank"
+        rel="noopener noreferrer"
+        aria-label={t("home.ui.feedback")}
+        className="fixed right-5 bottom-[calc(1.25rem+env(safe-area-inset-bottom))] z-50 flex items-center gap-2 rounded-full bg-ember-500 pl-3.5 pr-4 py-2.5 text-sm text-cream-50 shadow-lg transition-all hover:bg-clay-800 active:scale-95"
+      >
+        <i className="fa-solid fa-comment-dots text-[13px]" />
+        <span className="font-sans tracking-wide">{t("home.ui.feedback")}</span>
+      </a>
+
       {styleOpen && styleRow >= 0 && (
         <StyleModal
           items={OPTS[styleRow]!.items}

lib/i18n/locales/en.ts

@@ -119,6 +119,7 @@ export const en = {
       save: "Save",
       cancel: "Cancel",
       saveAndSelect: "Save and Select",
+      feedback: "Feedback",
     },
 
     styleModal: {

lib/i18n/locales/ja.ts

@@ -130,6 +130,7 @@ export const ja = {
       save: "保存",
       cancel: "キャンセル",
       saveAndSelect: "保存して適用",
+      feedback: "フィードバック",
     },
 
     // Style modal

lib/i18n/locales/zh-CN.ts

@@ -130,6 +130,7 @@ export const zhCN = {
       save: "保存",
       cancel: "取消",
       saveAndSelect: "保存并选用",
+      feedback: "反馈",
     },
 
     // Style modal