feat: integrate creator hub douyin workflows

internal/creator/collection_test.go

@@ -44,3 +44,26 @@ func TestCollectionWindowIsFixedInUTC(t *testing.T) {
 		t.Fatal("window must include both exact boundaries only")
 	}
 }
+
+func TestPublishedAtCollectionWindowRejectsFutureItems(t *testing.T) {
+	start := time.Date(2026, 3, 1, 0, 0, 0, 0, time.UTC)
+	end := start.Add(24 * time.Hour)
+	before, atStart, atEnd, after := start.Add(-time.Nanosecond), start, end, end.Add(time.Nanosecond)
+	for _, test := range []struct {
+		name string
+		at   *time.Time
+		want bool
+	}{
+		{name: "unknown", at: nil, want: true},
+		{name: "before", at: &before, want: false},
+		{name: "start", at: &atStart, want: true},
+		{name: "end", at: &atEnd, want: true},
+		{name: "future", at: &after, want: false},
+	} {
+		t.Run(test.name, func(t *testing.T) {
+			if got := publishedAtInCollectionWindow(test.at, start, end); got != test.want {
+				t.Fatalf("publishedAtInCollectionWindow(%v) = %v, want %v", test.at, got, test.want)
+			}
+		})
+	}
+}