feat: 章节软删除、对话左滑删除，移除已读状态

- 章节：详情页增加删除按钮，软删除（is_active=False），AI 不再修改但保留供参考
- 章节：get_chapter 增加 is_active 校验，已删除章节返回 404
- 章节：AI 生成时参考同类别已删除章节摘要
- 对话：左滑显示删除，调用 hard delete API，删除前二次确认
- 对话：根布局包裹 GestureHandlerRootView 以支持 Swipeable
- 对话：移除已读/未读状态展示及相关 i18n

app-expo/src/app/(main)/chapter/[id].tsx

@@ -1,10 +1,11 @@
 import { Image } from 'expo-image';
 import { LinearGradient } from 'expo-linear-gradient';
-import { useLocalSearchParams } from 'expo-router';
-import { Settings, X } from 'lucide-react-native';
+import { router, useLocalSearchParams } from 'expo-router';
+import { Settings, Trash2, X } from 'lucide-react-native';
 import React, { useEffect, useState } from 'react';
 import {
   ActivityIndicator,
+  Alert,
   Modal,
   Platform,
   Pressable,
@@ -20,7 +21,7 @@ import { Icon } from '@/components/ui/icon';
 import { Text } from '@/components/ui/text';
 import { ScreenHeader } from '@/components/screen-header';
 import { ScreenGutter } from '@/constants/layout';
-import { useChapterDetail } from '@/features/memoir/hooks';
+import { useChapterDetail, useDeleteChapter } from '@/features/memoir/hooks';
 
 // Life-Echo reading colors (from HTML reference)
 const READING_COLORS = {
@@ -536,6 +537,7 @@ export default function ChapterScreen() {
   const insets = useSafeAreaInsets();
   const { t } = useTranslation('memoir');
   const { data: chapter, isLoading } = useChapterDetail(id ?? '');
+  const deleteChapter = useDeleteChapter();
 
   const [settingsVisible, setSettingsVisible] = useState(false);
   const [fontSize, setFontSize] = useState<FontSize>('default');
@@ -568,6 +570,7 @@ export default function ChapterScreen() {
           alignItems: 'center',
           justifyContent: 'center',
           backgroundColor: bgColor,
+          gap: 16,
         }}
       >
         <Text
@@ -576,6 +579,25 @@ export default function ChapterScreen() {
         >
           {t('chapterReading.chapterNotFound')}
         </Text>
+        <Pressable
+          onPress={() => router.back()}
+          style={({ pressed }) => ({
+            paddingHorizontal: 20,
+            paddingVertical: 12,
+            borderRadius: 12,
+            backgroundColor: READING_COLORS.primary,
+            opacity: pressed ? 0.8 : 1,
+          })}
+          accessibilityRole="button"
+          accessibilityLabel={t('chapterReading.back')}
+        >
+          <Text
+            style={{ color: '#fff', fontSize: 16, fontWeight: '600' }}
+            selectable={false}
+          >
+            {t('chapterReading.back')}
+          </Text>
+        </Pressable>
       </View>
     );
   }
@@ -583,6 +605,25 @@ export default function ChapterScreen() {
   const sections = chapter.sections ?? [];
   const coverImageUrl = chapter.cover_image?.url ?? null;
 
+  const handleDeletePress = () => {
+    Alert.alert(
+      t('chapterReading.deleteChapter'),
+      t('chapterReading.confirmDeleteMessage'),
+      [
+        { text: t('chapterReading.cancel'), style: 'cancel' },
+        {
+          text: t('chapterReading.deleteChapterAction'),
+          style: 'destructive',
+          onPress: () => {
+            deleteChapter.mutate(chapter.id, {
+              onSuccess: () => router.back(),
+            });
+          },
+        },
+      ],
+    );
+  };
+
   return (
     <View style={{ flex: 1, backgroundColor: bgColor }}>
       <ScreenHeader
@@ -592,19 +633,38 @@ export default function ChapterScreen() {
         title={chapter.title}
         backAccessibilityLabel={t('chapterReading.back')}
         right={
-          <Pressable
-            onPress={() => setSettingsVisible(true)}
-            style={({ pressed }) => ({
-              padding: 8,
-              marginRight: -8,
-              borderRadius: 9999,
-              opacity: pressed ? 0.7 : 1,
-            })}
-            accessibilityLabel={t('chapterReading.settings')}
-            accessibilityRole="button"
-          >
-            <Icon as={Settings} size={24} color={READING_COLORS.primary} />
-          </Pressable>
+          <View style={{ flexDirection: 'row', alignItems: 'center', gap: 4 }}>
+            <Pressable
+              onPress={handleDeletePress}
+              disabled={deleteChapter.isPending}
+              style={({ pressed }) => ({
+                padding: 8,
+                borderRadius: 9999,
+                opacity: pressed ? 0.7 : 1,
+              })}
+              accessibilityLabel={t('chapterReading.deleteChapter')}
+              accessibilityRole="button"
+            >
+              <Icon
+                as={Trash2}
+                size={22}
+                color={READING_COLORS.onSurfaceVariant}
+              />
+            </Pressable>
+            <Pressable
+              onPress={() => setSettingsVisible(true)}
+              style={({ pressed }) => ({
+                padding: 8,
+                marginRight: -8,
+                borderRadius: 9999,
+                opacity: pressed ? 0.7 : 1,
+              })}
+              accessibilityLabel={t('chapterReading.settings')}
+              accessibilityRole="button"
+            >
+              <Icon as={Settings} size={24} color={READING_COLORS.primary} />
+            </Pressable>
+          </View>
         }
       />