test(x): 添加 x 目录下 inspector/metrics/monitor 的生命周期测试；修复 inspector 测试导入及 sqlite3 驱动注册，确保：

- 在本地有 Redis 时能运行完整集成测试
- 在无 Redis 环境下会自动跳过，避免破坏单元测试套件
同时补充了 metrics/monitor 的基本单元测试，改善测试的稳定性和可维护性

x/monitor/monitor_test.go

@@ -0,0 +1,48 @@
+package monitor
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"code.tczkiot.com/wlw/taskq/x/inspector"
+)
+
+func TestNewValidatesOptions(t *testing.T) {
+	_, err := New(Options{})
+	if err == nil {
+		t.Fatalf("expected error when options missing")
+	}
+
+	// valid case
+	ins := &inspector.Inspector{}
+	m, err := New(Options{Inspector: ins, Queues: map[string]int{"default": 1}})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if m.RootPath() != "/monitor" {
+		t.Fatalf("unexpected root path: %s", m.RootPath())
+	}
+}
+
+func TestHandleIndexServesUI(t *testing.T) {
+	ins := &inspector.Inspector{}
+	m, err := New(Options{Inspector: ins, Queues: map[string]int{"default": 1}, RootPath: "/my"})
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	req := httptest.NewRequest(http.MethodGet, "/my/", nil)
+	w := httptest.NewRecorder()
+	m.ServeHTTP(w, req)
+
+	resp := w.Result()
+	if resp.StatusCode != http.StatusOK {
+		t.Fatalf("expected 200 OK, got %d", resp.StatusCode)
+	}
+	// body should contain the root path replacement
+	body := w.Body.String()
+	if body == "" {
+		t.Fatalf("expected non-empty index body")
+	}
+}