feat: add clipboard paste, multi-image select, and file picker

- Add super_clipboard and file_picker dependencies
- Clipboard paste: reads PNG/JPEG image data from system clipboard
- Multi-image: pickMultiImage with remaining count limit
- File picker: supports images (jpg/png/gif/webp) and PDF files
- Updated attachment preview to show file icon for non-image types
- Bottom sheet now shows 4 options: gallery, camera, clipboard, file

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

it0_app/lib/features/chat/presentation/pages/chat_page.dart

@@ -1,7 +1,10 @@
 import 'dart:convert';
+import 'dart:io';
 import 'package:flutter/material.dart';
 import 'package:flutter_riverpod/flutter_riverpod.dart';
 import 'package:image_picker/image_picker.dart';
+import 'package:super_clipboard/super_clipboard.dart';
+import 'package:file_picker/file_picker.dart';
 import '../../../../core/theme/app_colors.dart';
 import '../../domain/entities/chat_message.dart';
 import '../providers/chat_providers.dart';
@@ -81,13 +84,25 @@ class _ChatPageState extends ConsumerState<ChatPage> {
             ListTile(
               leading: const Icon(Icons.photo_library),
               title: const Text('从相册选择'),
-              onTap: () { Navigator.pop(ctx); _pickImage(ImageSource.gallery); },
+              subtitle: const Text('支持多选'),
+              onTap: () { Navigator.pop(ctx); _pickMultipleImages(); },
             ),
             ListTile(
               leading: const Icon(Icons.camera_alt),
               title: const Text('拍照'),
               onTap: () { Navigator.pop(ctx); _pickImage(ImageSource.camera); },
             ),
+            ListTile(
+              leading: const Icon(Icons.content_paste),
+              title: const Text('从剪贴板粘贴'),
+              onTap: () { Navigator.pop(ctx); _pasteFromClipboard(); },
+            ),
+            ListTile(
+              leading: const Icon(Icons.attach_file),
+              title: const Text('选择文件'),
+              subtitle: const Text('图片、PDF'),
+              onTap: () { Navigator.pop(ctx); _pickFile(); },
+            ),
           ],
         ),
       ),
@@ -133,6 +148,145 @@ class _ChatPageState extends ConsumerState<ChatPage> {
     });
   }
 
+  Future<void> _pickMultipleImages() async {
+    final remaining = _maxAttachments - _pendingAttachments.length;
+    if (remaining <= 0) {
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('最多添加 $_maxAttachments 张图片')),
+        );
+      }
+      return;
+    }
+
+    final picker = ImagePicker();
+    final pickedList = await picker.pickMultiImage(
+      maxWidth: 1568,
+      maxHeight: 1568,
+      imageQuality: 85,
+    );
+    if (pickedList.isEmpty) return;
+
+    final toAdd = pickedList.take(remaining);
+    for (final picked in toAdd) {
+      final bytes = await picked.readAsBytes();
+      final ext = picked.path.split('.').last.toLowerCase();
+      final mediaType = switch (ext) {
+        'png' => 'image/png',
+        'webp' => 'image/webp',
+        'gif' => 'image/gif',
+        _ => 'image/jpeg',
+      };
+      _pendingAttachments.add(ChatAttachment(
+        base64Data: base64Encode(bytes),
+        mediaType: mediaType,
+        fileName: picked.name,
+      ));
+    }
+    setState(() {});
+
+    if (pickedList.length > remaining && mounted) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(content: Text('已选择 $remaining 张，最多 $_maxAttachments 张')),
+      );
+    }
+  }
+
+  Future<void> _pasteFromClipboard() async {
+    final clipboard = SystemClipboard.instance;
+    if (clipboard == null) {
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('当前设备不支持剪贴板读取')),
+        );
+      }
+      return;
+    }
+
+    try {
+      final reader = await clipboard.read();
+      for (final item in reader.items) {
+        // Try PNG first, then JPEG
+        for (final format in [Formats.png, Formats.jpeg]) {
+          if (item.canProvide(format)) {
+            final completer = item.getFile(format);
+            if (completer != null) {
+              final file = await completer;
+              final bytes = await file.readAll();
+              final mediaType = format == Formats.png ? 'image/png' : 'image/jpeg';
+              setState(() {
+                _pendingAttachments.add(ChatAttachment(
+                  base64Data: base64Encode(bytes),
+                  mediaType: mediaType,
+                  fileName: 'clipboard.${format == Formats.png ? "png" : "jpg"}',
+                ));
+              });
+              return;
+            }
+          }
+        }
+      }
+    } catch (e) {
+      // Clipboard read failed
+    }
+
+    if (mounted) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        const SnackBar(content: Text('剪贴板中没有图片')),
+      );
+    }
+  }
+
+  Future<void> _pickFile() async {
+    final remaining = _maxAttachments - _pendingAttachments.length;
+    if (remaining <= 0) {
+      if (mounted) {
+        ScaffoldMessenger.of(context).showSnackBar(
+          const SnackBar(content: Text('最多添加 $_maxAttachments 个附件')),
+        );
+      }
+      return;
+    }
+
+    final result = await FilePicker.platform.pickFiles(
+      type: FileType.custom,
+      allowedExtensions: ['jpg', 'jpeg', 'png', 'gif', 'webp', 'pdf'],
+      allowMultiple: true,
+    );
+    if (result == null || result.files.isEmpty) return;
+
+    final toAdd = result.files.take(remaining);
+    for (final file in toAdd) {
+      if (file.path == null) continue;
+      final bytes = await File(file.path!).readAsBytes();
+      final ext = (file.extension ?? '').toLowerCase();
+      final String mediaType;
+      if (ext == 'pdf') {
+        mediaType = 'application/pdf';
+      } else {
+        mediaType = switch (ext) {
+          'png' => 'image/png',
+          'webp' => 'image/webp',
+          'gif' => 'image/gif',
+          _ => 'image/jpeg',
+        };
+      }
+
+      _pendingAttachments.add(ChatAttachment(
+        base64Data: base64Encode(bytes),
+        mediaType: mediaType,
+        fileName: file.name,
+      ));
+    }
+    setState(() {});
+
+    if (result.files.length > remaining && mounted) {
+      ScaffoldMessenger.of(context).showSnackBar(
+        SnackBar(content: Text('已选择 $remaining 个，最多 $_maxAttachments 个')),
+      );
+    }
+  }
+
   Widget _buildAttachmentPreview() {
     return SizedBox(
       height: 80,
@@ -141,14 +295,36 @@ class _ChatPageState extends ConsumerState<ChatPage> {
         itemCount: _pendingAttachments.length,
         itemBuilder: (ctx, i) {
           final att = _pendingAttachments[i];
-          final bytes = base64Decode(att.base64Data);
+          final isImage = att.mediaType.startsWith('image/');
           return Stack(
             children: [
               Padding(
                 padding: const EdgeInsets.all(4),
                 child: ClipRRect(
                   borderRadius: BorderRadius.circular(8),
-                  child: Image.memory(bytes, width: 72, height: 72, fit: BoxFit.cover, cacheWidth: 144, cacheHeight: 144),
+                  child: isImage
+                      ? Image.memory(
+                          base64Decode(att.base64Data),
+                          width: 72, height: 72,
+                          fit: BoxFit.cover,
+                          cacheWidth: 144, cacheHeight: 144,
+                        )
+                      : Container(
+                          width: 72, height: 72,
+                          color: AppColors.surfaceLight,
+                          child: Column(
+                            mainAxisAlignment: MainAxisAlignment.center,
+                            children: [
+                              const Icon(Icons.description, size: 28, color: AppColors.textSecondary),
+                              const SizedBox(height: 2),
+                              Text(
+                                att.fileName?.split('.').last.toUpperCase() ?? 'FILE',
+                                style: const TextStyle(fontSize: 10, color: AppColors.textMuted),
+                                overflow: TextOverflow.ellipsis,
+                              ),
+                            ],
+                          ),
+                        ),
                 ),
               ),
               Positioned(

it0_app/pubspec.yaml

@@ -37,6 +37,8 @@ dependencies:
   gpt_markdown: ^1.1.5
   flutter_svg: ^2.0.10+1
   image_picker: ^1.1.2
+  super_clipboard: ^0.8.1
+  file_picker: ^8.0.0
 
   # Voice
   record: ^6.0.0