feat: initialize Ballet Island 微信小程序 with basic structure and functionality

- Add project configuration for WeChat mini program.
- Create skills lock file for Taroify integration.
- Set up app configuration and styles.
- Implement main app component and index page with welcome message.
- Add health check service to verify backend readiness.
- Configure TypeScript settings and global types.

backend/internal/httpapi/handler.go

@@ -0,0 +1,34 @@
+package httpapi
+
+import (
+	"context"
+	"encoding/json"
+	"net/http"
+	"time"
+)
+
+// NewHandler returns health endpoints. ping must honor its context deadline.
+func NewHandler(ping func(context.Context) error) http.Handler {
+	mux := http.NewServeMux()
+	mux.HandleFunc("GET /healthz", func(w http.ResponseWriter, r *http.Request) {
+		writeStatus(w, http.StatusOK, "ok")
+	})
+	mux.HandleFunc("GET /readyz", func(w http.ResponseWriter, r *http.Request) {
+		ctx, cancel := context.WithTimeout(r.Context(), 2*time.Second)
+		defer cancel()
+		if err := ping(ctx); err != nil {
+			// Do not expose database connection details through a public endpoint.
+			writeStatus(w, http.StatusServiceUnavailable, "unavailable")
+			return
+		}
+		writeStatus(w, http.StatusOK, "ok")
+	})
+	return mux
+}
+
+func writeStatus(w http.ResponseWriter, code int, status string) {
+	w.Header().Set("Content-Type", "application/json; charset=utf-8")
+	w.Header().Set("Cache-Control", "no-store")
+	w.WriteHeader(code)
+	_ = json.NewEncoder(w).Encode(map[string]string{"status": status})
+}