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.js

@@ -0,0 +1,13 @@
+Component({
+  properties: {
+    title: { type: String, value: '' },
+    subtitle: { type: String, value: '' },
+    eyebrow: { type: String, value: '' },
+    action: { type: String, value: '' }
+  },
+  methods: {
+    onAction() {
+      this.triggerEvent('action');
+    }
+  }
+});