refactor(ui): redesign SearchBar with compact mode and add home screen tabs

Refactor SearchBar component to support compact mode with transparent styling,
reduced padding, and smaller icons. Add home screen tab navigation for switching
between home feed and market view with animated tab indicator. Also adjust
PostDetailScreen action button sizing and CommentItem margins for better spacing.

app/_layout.tsx

@@ -8,6 +8,7 @@ import { PaperProvider } from 'react-native-paper';
 import { QueryClient, QueryClientProvider } from '@tanstack/react-query';
 import * as Notifications from 'expo-notifications';
 import * as SystemUI from 'expo-system-ui';
+import { useFonts } from 'expo-font';
 
 import { registerNotificationPresentationHandler } from '@/services/notification';
 import { api } from '@/services/core';
@@ -267,6 +268,16 @@ function ThemedProviders({ children }: { children: React.ReactNode }) {
 }
 
 export default function RootLayout() {
+  const [fontsLoaded] = useFonts({});
+
+  if (!fontsLoaded) {
+    return (
+      <View style={{ flex: 1, justifyContent: 'center', alignItems: 'center' }}>
+        <ActivityIndicator />
+      </View>
+    );
+  }
+
   return (
     <GestureHandlerRootView style={{ flex: 1 }}>
       <SafeAreaProvider>

app/trade/[tradeId].tsx

@@ -0,0 +1,7 @@
+import { TradeDetailScreen } from '../../src/screens/trade/TradeDetailScreen';
+import { useLocalSearchParams } from 'expo-router';
+
+export default function TradeDetailRoute() {
+  const { tradeId } = useLocalSearchParams<{ tradeId: string }>();
+  return <TradeDetailScreen tradeId={tradeId} />;
+}

app/trade/edit/[tradeId].tsx

@@ -0,0 +1,46 @@
+import { useCallback, useEffect, useState } from 'react';
+import { useLocalSearchParams, useRouter } from 'expo-router';
+import { CreateTradeScreen } from '../../../src/screens/trade/CreateTradeScreen';
+import { tradeService } from '../../../src/services/trade/tradeService';
+import { Loading } from '../../../src/components/common';
+import { View, Alert } from 'react-native';
+import type { TradeItemDetailDTO } from '../../../src/types/trade';
+
+export default function EditTradeRoute() {
+  const { tradeId } = useLocalSearchParams<{ tradeId: string }>();
+  const router = useRouter();
+  const [item, setItem] = useState<TradeItemDetailDTO | null>(null);
+  const [loading, setLoading] = useState(true);
+
+  useEffect(() => {
+    if (!tradeId) return;
+    tradeService.getTradeItem(tradeId)
+      .then(data => setItem(data))
+      .catch(() => Alert.alert('错误', '加载商品信息失败'))
+      .finally(() => setLoading(false));
+  }, [tradeId]);
+
+  const handleClose = useCallback(() => {
+    router.back();
+  }, [router]);
+
+  const handleSuccess = useCallback(() => {
+    router.back();
+  }, [router]);
+
+  if (loading) {
+    return <Loading fullScreen />;
+  }
+
+  if (!item) {
+    return null;
+  }
+
+  return (
+    <CreateTradeScreen
+      onClose={handleClose}
+      onSuccess={handleSuccess}
+      editItem={item}
+    />
+  );
+}