refactor(core): distinguish network errors from auth failures and refactor real-time messaging pipeline

- Add isNetworkError() helper and FetchCurrentUserResult discriminated union to prevent logout on network failures
- Refactor authService to return { kind: 'user' } | { kind: 'auth_failed' } | { kind: 'network_error' }
- Update authStore to preserve login state on network errors, only logout on auth failures
- Replace WSMessageHandler with RealtimeIngestionPipeline for improved real-time message handling
- Remove MessageDeduplication service; add store-level idempotent addOrReplaceMessage for message dedup
- Add atomic systemUnreadCount operations to prevent race conditions
- Add SearchHeader component for consistent search UI across screens
- Add 'home' TabBar variant with underline style matching HomeScreen
- Add Jest test infrastructure and exclude tests from tsconfig
- Fix ChatScreen history lock being stuck when scrolling to latest messages
- Remove unused call_participant_joined/left WS event types

src/components/business/TabBar.tsx

@@ -10,7 +10,7 @@ import { MaterialCommunityIcons } from '@expo/vector-icons';
 import { spacing, fontSizes, borderRadius, useAppColors, type AppColors } from '../../theme';
 import Text from '../common/Text';
 
-type TabBarVariant = 'default' | 'pill' | 'segmented' | 'modern';
+type TabBarVariant = 'default' | 'pill' | 'segmented' | 'modern' | 'home';
 
 interface TabBarProps {
   tabs: string[];
@@ -20,6 +20,8 @@ interface TabBarProps {
   rightContent?: ReactNode;
   variant?: TabBarVariant;
   icons?: string[];
+  /** home 变体的字号，默认 18（HomeScreen 可传 20） */
+  fontSize?: number;
   style?: StyleProp<ViewStyle>;
 }
 
@@ -176,6 +178,33 @@ function createTabBarStyles(colors: AppColors) {
       borderTopLeftRadius: borderRadius.sm,
       borderTopRightRadius: borderRadius.sm,
     },
+    // home 变体：与 HomeScreen/SearchScreen 一致的文字下划线风格
+    homeContainer: {
+      flexDirection: 'row',
+      alignItems: 'center',
+      backgroundColor: 'transparent',
+    },
+    homeTab: {
+      alignItems: 'center',
+      justifyContent: 'center',
+      paddingVertical: spacing.sm,
+      marginRight: 20,
+      borderBottomWidth: 2,
+      borderBottomColor: 'transparent',
+    },
+    homeTabActive: {
+      borderBottomColor: colors.text.primary,
+    },
+    homeTabText: {
+      fontSize: fontSizes.xl,
+      fontWeight: '400',
+      color: colors.text.hint,
+    },
+    homeTabTextActive: {
+      fontSize: fontSizes.xl,
+      fontWeight: '700',
+      color: colors.text.primary,
+    },
   });
 }
 
@@ -187,6 +216,7 @@ const TabBar: React.FC<TabBarProps> = ({
   rightContent,
   variant = 'default',
   icons,
+  fontSize,
   style,
 }) => {
   const colors = useAppColors();
@@ -278,6 +308,29 @@ const TabBar: React.FC<TabBarProps> = ({
         );
       }
 
+      if (variant === 'home') {
+        const homeTextStyle = [
+          isActive ? styles.homeTabTextActive : styles.homeTabText,
+          fontSize != null ? { fontSize } : undefined,
+        ];
+        return (
+          <TouchableOpacity
+            key={index}
+            style={[styles.homeTab, isActive && styles.homeTabActive]}
+            onPress={() => onTabChange(index)}
+            activeOpacity={0.7}
+          >
+            <Text
+              variant="body"
+              color={isActive ? colors.text.primary : colors.text.hint}
+              style={homeTextStyle}
+            >
+              {tab}
+            </Text>
+          </TouchableOpacity>
+        );
+      }
+
       return (
         <TouchableOpacity
           key={index}
@@ -306,6 +359,8 @@ const TabBar: React.FC<TabBarProps> = ({
         return styles.segmentedContainer;
       case 'modern':
         return styles.modernContainer;
+      case 'home':
+        return styles.homeContainer;
       default:
         return styles.container;
     }