feat: 更新标签页和新增探索页面

- 将标签页中的“首页”改为“探索”，并更新相关逻辑
- 新增探索页面，展示推荐文章和训练计划
- 优化教练页面的导航，确保用户体验一致性
- 移除不再使用的代码，简化项目结构
- 更新路由常量，确保路径管理集中化

app/(tabs)/_layout.tsx

@@ -19,7 +19,7 @@ export default function TabLayout() {
       initialRouteName="coach"
       screenOptions={({ route }) => {
         const routeName = route.name;
-        const isSelected = (routeName === 'index' && pathname === ROUTES.TAB_HOME) ||
+        const isSelected = (routeName === 'explore' && pathname === ROUTES.TAB_EXPLORE) ||
           (routeName === 'coach' && pathname === ROUTES.TAB_COACH) ||
           (routeName === 'statistics' && pathname === ROUTES.TAB_STATISTICS) ||
           pathname.includes(routeName);
@@ -40,7 +40,7 @@ export default function TabLayout() {
             // 基于 routeName 设置图标与标题，避免 tabBarIcon 的包装导致文字裁剪
             const getIconAndTitle = () => {
               switch (routeName) {
-                case 'index':
+                case 'explore':
                   return { icon: 'magnifyingglass.circle.fill', title: '发现' } as const;
                 case 'coach':
                   return { icon: 'person.3.fill', title: 'Bot' } as const;
@@ -157,7 +157,7 @@ export default function TabLayout() {
         }}
       />
       <Tabs.Screen
-        name="index"
+        name="explore"
         options={{
           title: '发现',
           tabBarIcon: ({ color }) => {

app/onboarding/index.tsx

@@ -1,5 +1,6 @@
 import { ThemedText } from '@/components/ThemedText';
 import { ThemedView } from '@/components/ThemedView';
+import { ROUTES } from '@/constants/Routes';
 import { useColorScheme } from '@/hooks/useColorScheme';
 import { useThemeColor } from '@/hooks/useThemeColor';
 import AsyncStorage from '@react-native-async-storage/async-storage';
@@ -13,7 +14,6 @@ import {
   TouchableOpacity,
   View
 } from 'react-native';
-import { ROUTES } from '@/constants/Routes';
 
 const { width, height } = Dimensions.get('window');
 
@@ -30,10 +30,10 @@ export default function WelcomeScreen() {
   const handleSkip = async () => {
     try {
       await AsyncStorage.setItem('@onboarding_completed', 'true');
-      router.replace(ROUTES.TAB_HOME);
+      router.replace(ROUTES.TAB_COACH);
     } catch (error) {
       console.error('保存引导状态失败:', error);
-      router.replace(ROUTES.TAB_HOME);
+      router.replace(ROUTES.TAB_COACH);
     }
   };
 

app/profile/goals.tsx

@@ -1,7 +1,6 @@
 import { HeaderBar } from '@/components/ui/HeaderBar';
 import { Colors } from '@/constants/Colors';
 import { useColorScheme } from '@/hooks/useColorScheme';
-import { Ionicons } from '@expo/vector-icons';
 import AsyncStorage from '@react-native-async-storage/async-storage';
 import * as Haptics from 'expo-haptics';
 import { useRouter } from 'expo-router';
@@ -305,50 +304,6 @@ export default function GoalsScreen() {
             <Text style={[styles.rangeHint, { color: colors.textMuted }]}>建议范围 {STEPS_RANGE.min.toLocaleString()}-{STEPS_RANGE.max.toLocaleString()}，步进 {STEPS_RANGE.step}</Text>
           </SectionCard>
 
-          <SectionCard
-            title="练习普拉提是为了什么"
-            subtitle="可多选"
-          >
-            <View style={styles.grid}>
-              {PURPOSE_OPTIONS.map((opt) => {
-                const active = purposes.includes(opt.id);
-                return (
-                  <TouchableOpacity
-                    key={opt.id}
-                    style={[
-                      styles.optionCard,
-                      {
-                        backgroundColor: active ? colors.primary : colors.card,
-                        borderColor: active ? colors.primary : colors.border,
-                      },
-                    ]}
-                    activeOpacity={0.9}
-                    onPress={() => togglePurpose(opt.id)}
-                  >
-                    <View style={styles.optionIconWrap}>
-                      <Ionicons
-                        name={opt.icon}
-                        size={20}
-                        color={active ? colors.onPrimary : colors.text}
-                      />
-                    </View>
-                    <Text
-                      numberOfLines={2}
-                      style={[
-                        styles.optionLabel,
-                        { color: active ? colors.onPrimary : colors.text },
-                      ]}
-                    >
-                      {opt.label}
-                    </Text>
-                  </TouchableOpacity>
-                );
-              })}
-            </View>
-            {purposes.length > 0 && (
-              <Text style={[styles.selectedHint, { color: colors.textSecondary }]}>已选择 {purposes.length} 项</Text>
-            )}
-          </SectionCard>
         </ScrollView>
       </SafeAreaView>
     </View>

constants/Routes.ts

@@ -1,7 +1,7 @@
 // 应用路由常量定义
 export const ROUTES = {
   // Tab路由
-  TAB_HOME: '/',
+  TAB_EXPLORE: '/explore',
   TAB_COACH: '/coach',
   TAB_STATISTICS: '/statistics',
   TAB_PERSONAL: '/personal',