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/cmd/server/main.go

@@ -0,0 +1,84 @@
+package main
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"log/slog"
+	"net/http"
+	"os"
+	"os/signal"
+	"syscall"
+	"time"
+
+	"ballet-island/backend/internal/httpapi"
+	"github.com/jackc/pgx/v5/pgxpool"
+)
+
+func main() {
+	slog.SetDefault(slog.New(slog.NewJSONHandler(os.Stdout, nil)))
+	if err := run(); err != nil {
+		slog.Error("server stopped", "error", err)
+		os.Exit(1)
+	}
+}
+
+func run() error {
+	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
+	defer stop()
+
+	for _, key := range []string{"PGHOST", "PGDATABASE", "PGUSER", "PGPASSWORD"} {
+		if os.Getenv(key) == "" {
+			return fmt.Errorf("%s is required", key)
+		}
+	}
+
+	// Use libpq environment variables so passwords need no URL escaping.
+	pool, err := pgxpool.New(ctx, "")
+	if err != nil {
+		return fmt.Errorf("configure database: %w", err)
+	}
+	defer pool.Close()
+
+	startupCtx, cancel := context.WithTimeout(ctx, 10*time.Second)
+	err = pool.Ping(startupCtx)
+	cancel()
+	if err != nil {
+		return fmt.Errorf("connect database: %w", err)
+	}
+
+	addr := os.Getenv("HTTP_ADDR")
+	if addr == "" {
+		addr = "127.0.0.1:8080"
+	}
+	server := &http.Server{
+		Addr:              addr,
+		Handler:           httpapi.NewHandler(pool.Ping),
+		ReadHeaderTimeout: 5 * time.Second,
+		ReadTimeout:       10 * time.Second,
+		WriteTimeout:      10 * time.Second,
+		IdleTimeout:       60 * time.Second,
+	}
+
+	serverErr := make(chan error, 1)
+	go func() {
+		slog.Info("server starting", "address", addr)
+		serverErr <- server.ListenAndServe()
+	}()
+
+	select {
+	case err := <-serverErr:
+		if !errors.Is(err, http.ErrServerClosed) {
+			return err
+		}
+	case <-ctx.Done():
+		slog.Info("server shutting down")
+		shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+		if err := server.Shutdown(shutdownCtx); err != nil {
+			_ = server.Close()
+			return fmt.Errorf("shutdown server: %w", err)
+		}
+	}
+	return nil
+}