refactor(P2/P3): 完成全部7批重构 — 模块化、SSE退避、无障碍、Zod校验、Server组件、Room关系化

批次A：重命名 + 路由拆分
- store.ts → roomRepository.ts，更新全部 import
- blindbox/plan/route.ts 精简为薄路由，业务逻辑抽取到 planActions.ts / planQueries.ts

批次B：blindboxPlanGen.ts 拆分（710行 → src/lib/plan/）
- agentPlan.ts：Agent 工具调用与系统提示
- legacyPlan.ts：非 Agent 备用生成逻辑
- ideaSelection.ts：Idea 筛选与 Slot 映射
- transitEnrichment.ts：交通信息查询与填充
- index.ts：runPlanGeneration 主入口

批次C：SSE 连接稳定性
- useRoomPolling.ts 加入指数退避重连（上限60s，含Jitter）
- plan/stream/route.ts 添加30s心跳 + abort信号清理

批次D：无障碍修复
- Modal：role=dialog、aria-modal、aria-labelledby
- AuthModal：aria-label关闭按钮、tablist/tab/aria-selected
- PlanItemEditModal、QrInviteModal：补全aria-label
- BlindboxPlan：图标按钮aria-label

批次E：Zod 引入
- src/lib/schemas/ai.ts：AI返回值 Schema（IdeaTagsSchema等5个）
- src/lib/schemas/requests.ts：请求体 Schema
- ai.ts 手工验证替换为 Zod safeParse

批次F：Server Components
- achievements/page.tsx → Server Component + AchievementsClient.tsx
- profile/page.tsx → Server Component + ProfileClient.tsx

批次G：Room 关系化模型
- prisma/schema.prisma：新增 RoomMember、RoomRestaurant、RoomLike、RoomSwipe 4张表
- migration：20260302010000_room_relational_model
- roomRepository.ts 完整重写（关系查询+应用锁）
- buildRoomStatus.ts 适配关系查询

测试：全部329个用例通过，修复68个因auth mock缺失导致的测试失败

src/components/AuthModal.tsx

@@ -121,21 +121,24 @@ export default function AuthModal({ open, onClose, onAuth, defaultTab = "login"
   };
 
   return (
-    <Modal open={open} onClose={onClose}>
+    <Modal open={open} onClose={onClose} titleId="auth-modal-title">
       <div className="mb-4 flex items-center justify-between">
-        <span className="text-lg font-bold text-heading">欢迎</span>
+        <span id="auth-modal-title" className="text-lg font-bold text-heading">欢迎</span>
         <button
           onClick={onClose}
+          aria-label="关闭"
           className="flex h-8 w-8 items-center justify-center rounded-full bg-elevated text-muted transition-colors active:bg-subtle"
         >
           <X size={16} />
         </button>
       </div>
 
-      <div className="flex gap-1 rounded-xl bg-elevated p-1">
+      <div role="tablist" className="flex gap-1 rounded-xl bg-elevated p-1">
         {(["login", "register"] as const).map((t) => (
           <button
             key={t}
+            role="tab"
+            aria-selected={tab === t}
             onClick={() => switchTab(t)}
             className={`relative flex-1 rounded-lg py-2 text-sm font-semibold transition-colors ${
               tab === t ? "text-heading" : "text-muted"

src/components/BlindboxPlan.tsx

@@ -160,6 +160,8 @@ export default function BlindboxPlan({
               <button
                 key={day.date}
                 onClick={() => setDayIndex(i)}
+                aria-label={day.date}
+                aria-pressed={i === dayIndex}
                 className={`rounded-full transition-all ${
                   i === dayIndex
                     ? "h-1.5 w-5 bg-purple-400"

src/components/Modal.tsx

@@ -10,6 +10,8 @@ interface ModalProps {
   onClose: () => void;
   children: React.ReactNode;
   variant?: ModalVariant;
+  /** Used for aria-labelledby; the element with this id should contain the dialog title */
+  titleId?: string;
 }
 
 const sheet = {
@@ -41,6 +43,7 @@ export default function Modal({
   onClose,
   children,
   variant = "sheet",
+  titleId,
 }: ModalProps) {
   const backdropRef = useRef<HTMLDivElement>(null);
   const v = variants[variant];
@@ -60,6 +63,9 @@ export default function Modal({
           }}
         >
           <motion.div
+            role="dialog"
+            aria-modal="true"
+            aria-labelledby={titleId}
             className={v.content}
             initial={v.initial}
             animate={v.animate}

src/components/PlanItemEditModal.tsx

@@ -70,7 +70,7 @@ export default function PlanItemEditModal({
         <div className="flex flex-col gap-4">
           <div className="flex items-center justify-between">
             <h3 className="text-sm font-bold text-heading">编辑活动</h3>
-            <button onClick={handleClose} className="text-muted active:text-foreground">
+            <button onClick={handleClose} aria-label="关闭" className="text-muted active:text-foreground">
               <X size={16} />
             </button>
           </div>

src/components/QrInviteModal.tsx

@@ -43,6 +43,7 @@ export default function QrInviteModal({
     <Modal open={open} onClose={onClose}>
       <button
         onClick={onClose}
+        aria-label="关闭"
         className="absolute right-4 top-4 flex h-8 w-8 items-center justify-center rounded-full bg-elevated text-muted transition-colors active:bg-subtle"
       >
         <X size={16} />