feat(backend): book list/detail/delete with embedded progress + cache cleanup

backend/internal/api/users_test.go

@@ -9,14 +9,11 @@ import (
 
 func adminToken(t *testing.T, h http.Handler) string {
 	t.Helper()
-	w := do(h, "POST", "/api/auth/login", "", map[string]string{"username": "alice", "password": "pw12345"})
-	var v struct{ Token string }
-	json.Unmarshal(w.Body.Bytes(), &v)
-	return v.Token
+	return loginAs(t, h, "alice", testPW)
 }
 
 func TestUserCRUD(t *testing.T) {
-	_, h := setupAPI(t)
+	_, _, h, _ := setupAPI(t)
 	tok := adminToken(t, h)
 	w := do(h, "POST", "/api/users", tok, map[string]string{"username": "carol", "password": "pw123456", "role": "member"})
 	if w.Code != 201 {
@@ -59,7 +56,7 @@ func TestUserCRUD(t *testing.T) {
 }
 
 func TestBadRoleRejected(t *testing.T) {
-	_, h := setupAPI(t)
+	_, _, h, _ := setupAPI(t)
 	tok := adminToken(t, h)
 	w := do(h, "POST", "/api/users", tok, map[string]string{"username": "e", "password": "pw123456", "role": "god"})
 	if w.Code != 400 {
@@ -76,4 +73,9 @@ func findID(rows []map[string]any, name string) float64 {
 	return 0
 }
 
-func itoa(v any) string { return strconv.FormatFloat(v.(float64), 'f', 0, 64) }
+func itoa(v any) string {
+	if i, ok := v.(int64); ok {
+		return strconv.FormatInt(i, 10) // DB 行里的 id (如 store.Library.ID)
+	}
+	return strconv.FormatFloat(v.(float64), 'f', 0, 64) // json.Unmarshal 出来的数字
+}