feat(miniprogram): Token 常量生成脚本 + useCanvasTokens hook (E2-1 Phase 2)

- 新增 scripts/generate-tokens.ts 从 SCSS 解析 CSS 变量生成 token-values.ts
- 新增 useCanvasTokens hook 供 Canvas 组件适老化/医生端切换
- vitest include 扩展覆盖 scripts/__tests__/
- 10 单元测试覆盖 SCSS 解析和变量替换

apps/miniprogram/package.json

@@ -4,6 +4,7 @@
   "private": true,
   "description": "HMS 健康管理平台患者小程序",
   "scripts": {
+    "generate-tokens": "tsx scripts/generate-tokens.ts",
     "build:weapp": "taro build --type weapp",
     "dev:weapp": "taro build --type weapp --watch",
     "lint": "eslint src/",