feat: import Chinese-localized Buzz source snapshot

Signed-off-by: cls_宁波本机 <908705107@qq.com>

mobile/lib/shared/widgets/avatar_image.dart

@@ -0,0 +1,176 @@
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_svg/flutter_svg.dart';
+
+import '../relay/relay.dart';
+
+/// A circular avatar that supports both remote URLs and inline image data.
+///
+/// Flutter's [NetworkImage] only loads network URLs, while desktop browsers also
+/// accept `data:image/*` sources directly. Agent emoji avatars are inline SVGs,
+/// so mobile must decode those before rendering them.
+class AvatarImage extends StatelessWidget {
+  final String? imageUrl;
+  final double radius;
+  final Color? backgroundColor;
+  final Widget fallback;
+
+  const AvatarImage({
+    super.key,
+    required this.imageUrl,
+    required this.radius,
+    required this.fallback,
+    this.backgroundColor,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return CircleAvatar(
+      radius: radius,
+      backgroundColor: backgroundColor,
+      child: ClipOval(
+        child: SizedBox.square(
+          dimension: radius * 2,
+          child: AvatarImageContent(imageUrl: imageUrl, fallback: fallback),
+        ),
+      ),
+    );
+  }
+}
+
+/// Image content for avatar surfaces whose shape is supplied by their parent.
+class AvatarImageContent extends StatefulWidget {
+  final String? imageUrl;
+  final Widget fallback;
+  final BoxFit fit;
+
+  const AvatarImageContent({
+    super.key,
+    required this.imageUrl,
+    required this.fallback,
+    this.fit = BoxFit.cover,
+  });
+
+  @override
+  State<AvatarImageContent> createState() => _AvatarImageContentState();
+}
+
+class _AvatarImageContentState extends State<AvatarImageContent> {
+  late _AvatarSource? _source = _AvatarSource.parse(widget.imageUrl);
+
+  @override
+  void didUpdateWidget(AvatarImageContent oldWidget) {
+    super.didUpdateWidget(oldWidget);
+    if (widget.imageUrl != oldWidget.imageUrl) {
+      _source = _AvatarSource.parse(widget.imageUrl);
+    }
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final centeredFallback = Center(child: widget.fallback);
+
+    return switch (_source) {
+      _EmojiAvatarSource(:final emoji, :final color) => ColoredBox(
+        color: color,
+        child: LayoutBuilder(
+          builder: (_, constraints) => Center(
+            child: Text(
+              emoji,
+              textScaler: TextScaler.noScaling,
+              style: TextStyle(
+                fontSize: constraints.biggest.shortestSide * 258 / 512,
+                height: 1,
+              ),
+            ),
+          ),
+        ),
+      ),
+      _SvgAvatarSource(:final svg) => SvgPicture.string(
+        svg,
+        fit: widget.fit,
+        placeholderBuilder: (_) => centeredFallback,
+        errorBuilder: (_, _, _) => centeredFallback,
+      ),
+      _RasterDataAvatarSource(:final bytes) => Image.memory(
+        bytes,
+        fit: widget.fit,
+        errorBuilder: (_, _, _) => centeredFallback,
+      ),
+      _NetworkAvatarSource(:final url) => MediaImage(
+        url: url,
+        fit: widget.fit,
+        errorBuilder: (_, _, _) => centeredFallback,
+      ),
+      null => centeredFallback,
+    };
+  }
+}
+
+sealed class _AvatarSource {
+  const _AvatarSource();
+
+  static _AvatarSource? parse(String? value) {
+    final url = value?.trim();
+    if (url == null || url.isEmpty) return null;
+    if (!url.startsWith('data:image/')) return _NetworkAvatarSource(url);
+
+    try {
+      final data = UriData.parse(url);
+      if (data.mimeType == 'image/svg+xml') {
+        final Uint8List bytes = data.contentAsBytes();
+        final svg = utf8.decode(bytes);
+        return _parseEmojiAvatar(svg) ?? _SvgAvatarSource(svg);
+      }
+      return _RasterDataAvatarSource(data.contentAsBytes());
+    } on FormatException {
+      return null;
+    }
+  }
+}
+
+_EmojiAvatarSource? _parseEmojiAvatar(String svg) {
+  final colorValue = RegExp(
+    r'<rect\b[^>]*\sfill="([^"]+)"',
+  ).firstMatch(svg)?[1];
+  final emojiValue = RegExp(r'<text\b[^>]*>(.*?)</text>').firstMatch(svg)?[1];
+  if (colorValue == null || emojiValue == null) return null;
+
+  final color = _parseHexColor(colorValue);
+  if (color == null) return null;
+  final emoji = emojiValue
+      .replaceAll('&gt;', '>')
+      .replaceAll('&lt;', '<')
+      .replaceAll('&amp;', '&');
+  return _EmojiAvatarSource(emoji, color);
+}
+
+Color? _parseHexColor(String value) {
+  final hex = value.startsWith('#') ? value.substring(1) : value;
+  if (!RegExp(r'^[0-9a-fA-F]{6}$').hasMatch(hex)) return null;
+  final rgb = int.tryParse(hex, radix: 16);
+  return rgb == null ? null : Color(0xFF000000 | rgb);
+}
+
+class _EmojiAvatarSource extends _AvatarSource {
+  final String emoji;
+  final Color color;
+  const _EmojiAvatarSource(this.emoji, this.color);
+}
+
+class _SvgAvatarSource extends _AvatarSource {
+  final String svg;
+  const _SvgAvatarSource(this.svg);
+}
+
+class _RasterDataAvatarSource extends _AvatarSource {
+  final Uint8List bytes;
+  const _RasterDataAvatarSource(this.bytes);
+}
+
+class _NetworkAvatarSource extends _AvatarSource {
+  final String url;
+  const _NetworkAvatarSource(this.url);
+}