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/navbar/index.wxss

@@ -0,0 +1,29 @@
+.navbar {
+  background: linear-gradient(180deg, rgba(22,32,27,0.96) 0%, rgba(14,17,16,0.55) 100%);
+  position: sticky;
+  top: 0;
+  z-index: 50;
+}
+.navbar__status { width: 100%; }
+.navbar__bar {
+  height: 88rpx;
+  display: flex;
+  align-items: center;
+  position: relative;
+  padding: 0 28rpx;
+}
+.navbar__back {
+  font-size: 56rpx;
+  color: var(--gold);
+  line-height: 1;
+  width: 60rpx;
+}
+.navbar__title {
+  position: absolute;
+  left: 0; right: 0;
+  text-align: center;
+  font-size: 34rpx;
+  font-weight: 700;
+  letter-spacing: 2rpx;
+  color: var(--text);
+}