feat(export): 多会话导出布局选择与无媒体直出

- 多会话媒体导出支持共享/分会话目录
- 无媒体导出时直接输出到目标目录

src/pages/ExportPage.scss

@@ -602,6 +602,87 @@
     }
   }
 
+  .export-layout-modal {
+    background: var(--card-bg);
+    padding: 28px 32px;
+    border-radius: 16px;
+    box-shadow: 0 20px 60px rgba(0, 0, 0, 0.25);
+    text-align: center;
+    width: min(520px, 90vw);
+
+    h3 {
+      font-size: 18px;
+      font-weight: 600;
+      color: var(--text-primary);
+      margin: 0 0 8px;
+    }
+
+    .layout-subtitle {
+      font-size: 14px;
+      color: var(--text-secondary);
+      margin: 0 0 20px;
+    }
+
+    .layout-options {
+      display: grid;
+      gap: 12px;
+    }
+
+    .layout-option-btn {
+      display: flex;
+      flex-direction: column;
+      gap: 6px;
+      padding: 14px 18px;
+      border-radius: 12px;
+      border: 1px solid var(--border-color);
+      background: var(--bg-secondary);
+      text-align: left;
+      cursor: pointer;
+      transition: all 0.2s;
+
+      &:hover {
+        border-color: var(--primary);
+        background: rgba(var(--primary-rgb), 0.08);
+      }
+
+      &.primary {
+        border-color: var(--primary);
+        background: rgba(var(--primary-rgb), 0.12);
+      }
+
+      .layout-title {
+        font-size: 15px;
+        font-weight: 600;
+        color: var(--text-primary);
+      }
+
+      .layout-desc {
+        font-size: 12px;
+        color: var(--text-tertiary);
+      }
+    }
+
+    .layout-actions {
+      margin-top: 18px;
+      display: flex;
+      justify-content: center;
+    }
+
+    .layout-cancel-btn {
+      padding: 8px 20px;
+      border-radius: 8px;
+      border: 1px solid var(--border-color);
+      background: var(--bg-secondary);
+      color: var(--text-primary);
+      cursor: pointer;
+      transition: all 0.2s;
+
+      &:hover {
+        background: var(--bg-hover);
+      }
+    }
+  }
+
   .export-result-modal {
     background: var(--card-bg);
     padding: 32px 40px;
@@ -1056,4 +1137,4 @@
   input:checked + .slider::before {
     transform: translateX(20px);
   }
-}
+}

src/pages/ExportPage.tsx

@@ -31,6 +31,8 @@ interface ExportResult {
   error?: string
 }
 
+type SessionLayout = 'shared' | 'per-session'
+
 function ExportPage() {
   const [sessions, setSessions] = useState<ChatSession[]>([])
   const [filteredSessions, setFilteredSessions] = useState<ChatSession[]>([])
@@ -44,6 +46,7 @@ function ExportPage() {
   const [showDatePicker, setShowDatePicker] = useState(false)
   const [calendarDate, setCalendarDate] = useState(new Date())
   const [selectingStart, setSelectingStart] = useState(true)
+  const [showMediaLayoutPrompt, setShowMediaLayoutPrompt] = useState(false)
 
   const [options, setOptions] = useState<ExportOptions>({
     format: 'excel',
@@ -212,7 +215,7 @@ function ExportPage() {
     }
   }
 
-  const startExport = async () => {
+  const runExport = async (sessionLayout: SessionLayout) => {
     if (selectedSessions.size === 0 || !exportFolder) return
 
     setIsExporting(true)
@@ -228,11 +231,12 @@ function ExportPage() {
         exportImages: options.exportMedia && options.exportImages,
         exportVoices: options.exportMedia && options.exportVoices,
         exportEmojis: options.exportMedia && options.exportEmojis,
-        exportVoiceAsText: options.exportVoiceAsText,  // 独立于 exportMedia
+        exportVoiceAsText: options.exportVoiceAsText,  // ?????????exportMedia
         excelCompactColumns: options.excelCompactColumns,
+        sessionLayout,
         dateRange: options.useAllTime ? null : options.dateRange ? {
           start: Math.floor(options.dateRange.start.getTime() / 1000),
-          // 将结束日期设置为当天的 23:59:59,以包含当天的所有消息
+          // ?????????????????????????????????23:59:59,??????????????????????????????
           end: Math.floor(new Date(options.dateRange.end.getFullYear(), options.dateRange.end.getMonth(), options.dateRange.end.getDate(), 23, 59, 59).getTime() / 1000)
         } : null
       }
@@ -245,16 +249,28 @@ function ExportPage() {
         )
         setExportResult(result)
       } else {
-        setExportResult({ success: false, error: `${options.format.toUpperCase()} 格式导出功能开发中...` })
+        setExportResult({ success: false, error: `${options.format.toUpperCase()} ???????????????????????????...` })
       }
     } catch (e) {
-      console.error('导出失败:', e)
+      console.error('????????????:', e)
       setExportResult({ success: false, error: String(e) })
     } finally {
       setIsExporting(false)
     }
   }
 
+  const startExport = () => {
+    if (selectedSessions.size === 0 || !exportFolder) return
+
+    if (options.exportMedia && selectedSessions.size > 1) {
+      setShowMediaLayoutPrompt(true)
+      return
+    }
+
+    const layout: SessionLayout = options.exportMedia ? 'per-session' : 'shared'
+    runExport(layout)
+  }
+
   const getDaysInMonth = (date: Date) => {
     const year = date.getFullYear()
     const month = date.getMonth()
@@ -613,6 +629,43 @@ function ExportPage() {
         </div>
       </div>
 
+      {/* 媒体导出布局选择弹窗 */}
+      {showMediaLayoutPrompt && (
+        <div className="export-overlay" onClick={() => setShowMediaLayoutPrompt(false)}>
+          <div className="export-layout-modal" onClick={e => e.stopPropagation()}>
+            <h3>导出文件夹布局</h3>
+            <p className="layout-subtitle">检测到同时导出多个会话并包含媒体文件，请选择存放方式：</p>
+            <div className="layout-options">
+              <button
+                className="layout-option-btn primary"
+                onClick={() => {
+                  setShowMediaLayoutPrompt(false)
+                  runExport('shared')
+                }}
+              >
+                <span className="layout-title">所有会话在同一文件夹</span>
+                <span className="layout-desc">媒体会按会话名归档到 media 子目录</span>
+              </button>
+              <button
+                className="layout-option-btn"
+                onClick={() => {
+                  setShowMediaLayoutPrompt(false)
+                  runExport('per-session')
+                }}
+              >
+                <span className="layout-title">每个会话一个文件夹</span>
+                <span className="layout-desc">每个会话单独包含导出文件和媒体</span>
+              </button>
+            </div>
+            <div className="layout-actions">
+              <button className="layout-cancel-btn" onClick={() => setShowMediaLayoutPrompt(false)}>
+                取消
+              </button>
+            </div>
+          </div>
+        </div>
+      )}
+
       {/* 导出进度弹窗 */}
       {isExporting && (
         <div className="export-overlay">