fix+feat(ux): 已存草稿显示已保存(Q6) + AI 推理动画指示器(A)

- Q6 bug: useAutosave 加 initialSavedText，进页种入已存草稿时初始即「已保存」，修「加载已存草稿却显示尚未保存」的误导。
- A: 新 ThinkingIndicator（三点波动，motion-safe 尊重 reduced-motion）接入审稿进行中/验收中/回炉中三处静态文案，长等待看得见在工作。

apps/web/components/review/AcceptPanel.tsx

@@ -2,6 +2,7 @@
 
 import type { AcceptResponse } from "@/lib/api/types";
 import { buildAcceptPreview } from "@/lib/review/accept-preview";
+import { ThinkingIndicator } from "@/components/ThinkingIndicator";
 
 interface AcceptPanelProps {
   conflictCount: number;
@@ -101,7 +102,11 @@ export function AcceptPanel({
         aria-disabled={blocked || accepting}
         className="w-full rounded bg-cinnabar px-4 py-2 text-sm text-panel hover:opacity-90 disabled:cursor-not-allowed disabled:opacity-40"
       >
-        {accepting ? "验收中…" : "全部处理完 → 验收本章"}
+        {accepting ? (
+          <ThinkingIndicator label="验收中" className="justify-center" />
+        ) : (
+          "全部处理完 → 验收本章"
+        )}
       </button>
     </div>
   );