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/components/section-header/index.wxss

@@ -0,0 +1,23 @@
+.sh {
+  display: flex;
+  align-items: flex-end;
+  justify-content: space-between;
+  padding: 8rpx 0 20rpx;
+}
+.sh__title {
+  font-size: 40rpx;
+  font-weight: 700;
+  letter-spacing: 2rpx;
+  color: var(--text);
+  margin-top: 8rpx;
+}
+.sh__sub {
+  font-size: 24rpx;
+  color: var(--text-2);
+  margin-top: 8rpx;
+}
+.sh__action {
+  font-size: 26rpx;
+  color: var(--gold);
+  white-space: nowrap;
+}