refactor(ui): implement custom header system and unify screen layouts

Refactor the navigation and header strategy by replacing native stack headers with a custom `SimpleHeader` component across most profile and detail screens. This provides a more consistent UI/UX and better control over layout behavior.

- Implement `SimpleHeader` component in `src/components/common`.
- Disable native header rendering in `app/(app)/(tabs)/profile/_layout.tsx` and `app/_layout.tsx`.
- Update profile sub-screens to use `SimpleHeader` and `StatusBar` from `expo-status-bar`.
- Refactor `PostDetailScreen` to use a custom header implementation for better integration with the post author information.
- Update `UserScreen` to wrap content in `SafeAreaView` with the new header.
- Adjust `AppBackButton` to support transparent backgrounds.

src/screens/profile/EditProfileScreen.tsx

@@ -18,6 +18,8 @@ import {
 } from 'react-native';
 import { SafeAreaView, useSafeAreaInsets } from 'react-native-safe-area-context';
 import { useNavigation } from '@react-navigation/native';
+import { useRouter } from 'expo-router';
+import { StatusBar } from 'expo-status-bar';
 import { MaterialCommunityIcons } from '@expo/vector-icons';
 import * as ImagePicker from 'expo-image-picker';
 import {
@@ -28,7 +30,7 @@ import {
   type AppColors,
 } from '../../theme';
 import { useAuthStore } from '../../stores';
-import { Avatar, Text } from '../../components/common';
+import { Avatar, Text, SimpleHeader } from '../../components/common';
 import { authService, uploadService } from '../../services';
 import { useResponsive, useResponsiveSpacing } from '../../hooks';
 
@@ -276,6 +278,7 @@ export const EditProfileScreen: React.FC = () => {
   const colors = useAppColors();
   const styles = useMemo(() => createEditProfileStyles(colors), [colors]);
   const navigation = useNavigation();
+  const router = useRouter();
   const { currentUser, updateUser } = useAuthStore();
   const { isWideScreen, isMobile, width } = useResponsive();
   const responsivePadding = useResponsiveSpacing({ xs: 0, sm: 0, md: 0, lg: 24, xl: 32 });
@@ -596,7 +599,9 @@ export const EditProfileScreen: React.FC = () => {
   );
 
   return (
-    <SafeAreaView style={styles.container} edges={['bottom']}>
+    <SafeAreaView style={styles.container} edges={['top', 'bottom']}>
+      <StatusBar style="auto" />
+      <SimpleHeader title="编辑资料" onBack={() => router.back()} />
       <KeyboardAvoidingView
         behavior={Platform.OS === 'ios' ? 'padding' : 'height'}
         style={styles.keyboardView}