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})
+}

backend/internal/httpapi/handler_test.go

@@ -0,0 +1,67 @@
+package httpapi
+
+import (
+	"context"
+	"errors"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+	"time"
+)
+
+func TestHealthRemainsLiveWithoutDatabase(t *testing.T) {
+	handler := NewHandler(func(context.Context) error {
+		t.Fatal("liveness must not query the database")
+		return nil
+	})
+	response := httptest.NewRecorder()
+	handler.ServeHTTP(response, httptest.NewRequest(http.MethodGet, "/healthz", nil))
+	if response.Code != http.StatusOK || response.Body.String() != "{\"status\":\"ok\"}\n" {
+		t.Fatalf("unexpected response: %d %s", response.Code, response.Body.String())
+	}
+}
+
+func TestReadinessReflectsDatabaseState(t *testing.T) {
+	for _, tc := range []struct {
+		name string
+		err  error
+		code int
+		body string
+	}{
+		{"ready", nil, http.StatusOK, "{\"status\":\"ok\"}\n"},
+		{"unavailable", errors.New("private database details"), http.StatusServiceUnavailable, "{\"status\":\"unavailable\"}\n"},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+			called := false
+			handler := NewHandler(func(ctx context.Context) error {
+				called = true
+				deadline, ok := ctx.Deadline()
+				if !ok || time.Until(deadline) > 2*time.Second {
+					t.Fatal("database check must have a bounded deadline")
+				}
+				return tc.err
+			})
+			response := httptest.NewRecorder()
+			handler.ServeHTTP(response, httptest.NewRequest(http.MethodGet, "/readyz", nil))
+			if !called || response.Code != tc.code || response.Body.String() != tc.body {
+				t.Fatalf("unexpected response: %d %s", response.Code, response.Body.String())
+			}
+			if !strings.HasPrefix(response.Header().Get("Content-Type"), "application/json") {
+				t.Fatal("health response must be JSON")
+			}
+		})
+	}
+}
+
+func TestReadinessPreservesRequestCancellation(t *testing.T) {
+	ctx, cancel := context.WithCancel(context.Background())
+	cancel()
+	handler := NewHandler(func(ctx context.Context) error { return ctx.Err() })
+	response := httptest.NewRecorder()
+	request := httptest.NewRequest(http.MethodGet, "/readyz", nil).WithContext(ctx)
+	handler.ServeHTTP(response, request)
+	if response.Code != http.StatusServiceUnavailable {
+		t.Fatalf("got %d, want 503", response.Code)
+	}
+}