refactor: unify design-system components across pages

- Replace native textarea with Textarea in translator and text-speaker pages
- Replace custom loading spinners with Skeleton in InDeck and FavoritesClient pages
- Add shared constants DEFAULT_NEW_PER_DAY, DEFAULT_REV_PER_DAY

src/app/(features)/favorites/FavoritesClient.tsx

@@ -12,6 +12,8 @@ import { toast } from "sonner";
 import { PageLayout } from "@/components/ui/PageLayout";
 import { PageHeader } from "@/components/ui/PageHeader";
 import { CardList } from "@/components/ui/CardList";
+import { VStack } from "@/design-system/layout/stack";
+import { Skeleton } from "@/design-system/feedback/skeleton";
 import { actionGetUserFavoriteDecks, actionToggleDeckFavorite } from "@/modules/deck/deck-action";
 import type { ActionOutputUserFavoriteDeck } from "@/modules/deck/deck-action-dto";
 
@@ -102,10 +104,10 @@ export function FavoritesClient({ initialFavorites }: FavoritesClientProps) {
 
       <CardList>
         {loading ? (
-          <div className="p-8 text-center">
-            <div className="w-8 h-8 border-2 border-gray-200 border-t-gray-400 rounded-full animate-spin mx-auto mb-3"></div>
+          <VStack align="center" className="p-8">
+            <Skeleton variant="circular" className="w-8 h-8" />
             <p className="text-sm text-gray-500">{t("loading")}</p>
-          </div>
+          </VStack>
         ) : favorites.length === 0 ? (
           <div className="text-center py-12 text-gray-400">
             <div className="w-16 h-16 mx-auto mb-3 rounded-full bg-gray-100 flex items-center justify-center">

src/app/(features)/text-speaker/page.tsx

@@ -1,7 +1,7 @@
 "use client";
 
-import { LightButton } from "@/design-system/base/button";
-import { IconClick } from "@/design-system/base/button";
+import { LightButton, IconClick } from "@/design-system/base/button";
+import { Textarea } from "@/design-system/base/textarea";
 import { IMAGES } from "@/config/images";
 import { useAudioPlayer } from "@/hooks/useAudioPlayer";
 import {
@@ -226,11 +226,12 @@ export default function TextSpeakerPage() {
         style={{ fontFamily: "Times New Roman, serif" }}
       >
         {/* 文本输入框 */}
-        <textarea
-          className="text-2xl resize-none focus:outline-0 min-h-64 w-full border-gray-200 border-b p-4"
+        <Textarea
+          variant="bordered"
+          className="text-2xl min-h-64"
           onChange={handleInputChange}
           ref={textareaRef}
-        ></textarea>
+        />
         {/* IPA 显示区域 */}
         {(ipa.length !== 0 && (
           <div className="overflow-auto text-gray-600 h-18 border-gray-200 border-b px-4">

src/app/(features)/translator/page.tsx

@@ -1,7 +1,9 @@
 "use client";
 
-import { LightButton, PrimaryButton, IconClick } from "@/design-system/base/button";
+import { LightButton, PrimaryButton,
+ IconClick } from "@/design-system/base/button";
 import { Select } from "@/design-system/base/select";
+import { Textarea } from "@/design-system/base/textarea";
 import { IMAGES } from "@/config/images";
 import { useAudioPlayer } from "@/hooks/useAudioPlayer";
 import { useTranslations } from "next-intl";
@@ -134,13 +136,13 @@ export default function TranslatorPage() {
         <div className="w-full md:w-1/2 flex flex-col-reverse gap-2">
           {/* ICard1 Component */}
           <div className="border border-gray-200 rounded-lg w-full h-64 p-2">
-            <textarea
-              className="resize-none h-8/12 w-full focus:outline-0"
+            <Textarea
+              className="resize-none h-8/12 w-full"
               ref={taref}
               onKeyDown={(e) => {
                 if (e.ctrlKey && e.key === "Enter") translate();
               }}
-            ></textarea>
+            />
             <div className="ipa w-full h-2/12 overflow-auto text-gray-600">
               {translationResult?.sourceIpa || ""}
             </div>

src/app/decks/[deck_id]/InDeck.tsx

@@ -11,7 +11,8 @@ import { PrimaryButton, CircleButton, LinkButton, LightButton } from "@/design-s
 import { CardList } from "@/components/ui/CardList";
 import { Modal } from "@/design-system/overlay/modal";
 import { Input } from "@/design-system/base/input";
-import { HStack } from "@/design-system/layout/stack";
+import { HStack, VStack } from "@/design-system/layout/stack";
+import { Skeleton } from "@/design-system/feedback/skeleton";
 import { actionGetCardsByDeckIdWithNotes, actionDeleteCard, actionResetDeckCards, actionGetTodayStudyStats } from "@/modules/card/card-action";
 import { actionGetDeckById, actionUpdateDeck } from "@/modules/deck/deck-action";
 import type { ActionOutputCardWithNote } from "@/modules/card/card-action-dto";
@@ -188,10 +189,10 @@ export function InDeck({ deckId, isReadOnly }: { deckId: number; isReadOnly: boo
 
       <CardList>
         {loading ? (
-          <div className="p-8 text-center">
-            <div className="w-8 h-8 border-2 border-gray-200 border-t-gray-400 rounded-full animate-spin mx-auto mb-3"></div>
+          <VStack align="center" className="p-8">
+            <Skeleton variant="circular" className="w-8 h-8" />
             <p className="text-sm text-gray-500">{t("loadingCards")}</p>
-          </div>
+          </VStack>
         ) : cards.length === 0 ? (
           <div className="p-12 text-center">
             <p className="text-sm text-gray-500 mb-2">{t("noCards")}</p>