feat: init fitness-coach (backend + miniprogram)

- backend: NestJS service with exercise/plan data
- miniprogram: WeChat mini program client
- exclude node_modules, dist, runtime data-store, local env

backend/package.json

@@ -0,0 +1,35 @@
+{
+  "name": "fitness-coach-backend",
+  "version": "1.0.0",
+  "description": "健身动作推荐小程序 - NestJS 后端代理与数据服务",
+  "author": "WorkBuddy",
+  "private": true,
+  "license": "MIT",
+  "scripts": {
+    "prebuild": "node scripts/ensure-data.mjs",
+    "build": "nest build && node scripts/copy-data.mjs",
+    "start": "nest start",
+    "dev": "nest start --watch",
+    "start:prod": "node dist/main.js",
+    "sync:media": "node scripts/sync-media.mjs",
+    "lint": "eslint \"{src,apps,libs,test}/**/*.ts\" --fix"
+  },
+  "dependencies": {
+    "@nestjs/common": "^10.4.4",
+    "@nestjs/core": "^10.4.4",
+    "@nestjs/platform-express": "^10.4.4",
+    "@nestjs/serve-static": "^4.0.2",
+    "class-transformer": "^0.5.1",
+    "class-validator": "^0.14.1",
+    "reflect-metadata": "^0.2.2",
+    "rxjs": "^7.8.1"
+  },
+  "devDependencies": {
+    "@nestjs/cli": "^10.4.5",
+    "@nestjs/schematics": "^10.1.4",
+    "@nestjs/testing": "^10.4.4",
+    "@types/express": "^4.17.21",
+    "@types/node": "^20.14.0",
+    "typescript": "^5.5.4"
+  }
+}