feat: Features架构迁移 - P0和P1部分完成

## 完成的工作

### P0: 基础设施准备
- 创建 features/ 和 shared/ 目录结构
- 迁移共享资源：API基础设施、工具函数、类型定义
- 迁移通用composables：useMoney, useSmsCountdown, usePricingCalculator
- 迁移全局样式文件
- 建立模块化导出系统

### P1.1: 钱包模块 (wallet)
- 迁移 API: wallet.ts
- 迁移 Views: WalletView.vue
- 新增 Composable: useWallet.ts (封装钱包状态管理)
- 更新导入路径到 shared/

### P1.2: 聊天模块 (chats)
- 迁移 API: chats.ts
- 迁移 Views: ChatView, MessagesView (桌面+移动)
- 迁移 Composables: useChatSSE.ts
- 迁移 Components: ChatAttachmentImage.vue
- 更新导入路径到 shared/

## 技术改进
- 修复 shared/composables 导出问题 (default → 命名导出)
- 修复 shared/api/client.ts 类型导入路径
- 建立清晰的模块边界和导出规范

## 文档
- 添加完整的迁移计划文档
- 添加进度跟踪文档

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/shared/utils/imageUpload.ts

@@ -0,0 +1,84 @@
+const IMAGE_UPLOAD_MAX_SIDE: Record<string, number> = {
+  avatar: 512,
+  chat: 1280,
+  "home-banner": 1920,
+  listing: 1920,
+  dispute: 1920,
+  handoff: 1920,
+  realname: 1920,
+};
+
+const IMAGE_UPLOAD_QUALITY: Record<string, number> = {
+  avatar: 0.82,
+  chat: 0.8,
+  "home-banner": 0.84,
+  listing: 0.84,
+  dispute: 0.86,
+  handoff: 0.86,
+  realname: 0.86,
+};
+
+export async function optimizeImageForUpload(file: File, scene: string) {
+  if (!file.type.startsWith("image/")) return file;
+  if (!["image/jpeg", "image/png", "image/webp"].includes(file.type)) return file;
+  if (typeof document === "undefined") return file;
+
+  try {
+    const image = await loadImage(file);
+    const maxSide = IMAGE_UPLOAD_MAX_SIDE[scene] || 1600;
+    const quality = IMAGE_UPLOAD_QUALITY[scene] || 0.82;
+    const { width, height } = fitSize(image.naturalWidth, image.naturalHeight, maxSide);
+    const canvas = document.createElement("canvas");
+    canvas.width = width;
+    canvas.height = height;
+    const context = canvas.getContext("2d");
+    if (!context) return file;
+    context.fillStyle = "#ffffff";
+    context.fillRect(0, 0, width, height);
+    context.drawImage(image, 0, 0, width, height);
+    const blob = await canvasToBlob(canvas, "image/webp", quality);
+    if (!blob || blob.size >= file.size) return file;
+    return new File([blob], replaceFileExt(file.name, "webp"), {
+      type: "image/webp",
+      lastModified: Date.now(),
+    });
+  } catch {
+    return file;
+  }
+}
+
+function loadImage(file: File) {
+  return new Promise<HTMLImageElement>((resolve, reject) => {
+    const url = URL.createObjectURL(file);
+    const image = new Image();
+    image.onload = () => {
+      URL.revokeObjectURL(url);
+      resolve(image);
+    };
+    image.onerror = () => {
+      URL.revokeObjectURL(url);
+      reject(new Error("图片读取失败"));
+    };
+    image.src = url;
+  });
+}
+
+function fitSize(width: number, height: number, maxSide: number) {
+  if (width <= 0 || height <= 0) return { width: 1, height: 1 };
+  const scale = Math.min(1, maxSide / Math.max(width, height));
+  return {
+    width: Math.max(1, Math.round(width * scale)),
+    height: Math.max(1, Math.round(height * scale)),
+  };
+}
+
+function canvasToBlob(canvas: HTMLCanvasElement, type: string, quality: number) {
+  return new Promise<Blob | null>((resolve) => {
+    canvas.toBlob(resolve, type, quality);
+  });
+}
+
+function replaceFileExt(filename: string, ext: string) {
+  const base = filename.replace(/\.[^.]+$/, "");
+  return `${base || "image"}.${ext}`;
+}