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

miniprogram/pages/search/search.wxss

@@ -0,0 +1,14 @@
+.page { min-height: 100vh; background: var(--bg-grad); }
+.searchbar { padding: 12rpx 32rpx; }
+.searchbar__box {
+  display: flex; align-items: center;
+  background: var(--surface); border: 1rpx solid var(--line);
+  border-radius: 999rpx; padding: 20rpx 28rpx;
+}
+.searchbar__icon { font-size: 30rpx; margin-right: 16rpx; }
+.searchbar__input { flex: 1; color: var(--text); font-size: 28rpx; }
+.ph { color: var(--text-3); }
+
+.grid { display: flex; flex-wrap: wrap; gap: 18rpx; }
+.grid__item { width: calc((100% - 18rpx) / 2); }
+.empty { color: var(--text-3); font-size: 26rpx; text-align: center; padding: 120rpx 0; }