fix: sync star gift profile pin order

Sync telesrv 6fcc6f0 (fix(stargifts): honor profile pin order).

Skipped telesrv docs changes per public sync rules.

internal/domain/star_gift_cursor_test.go

@@ -0,0 +1,31 @@
+package domain
+
+import "testing"
+
+func TestSavedStarGiftListCursorRoundTrip(t *testing.T) {
+	want := SavedStarGiftListCursor{PinnedOrder: 7, ID: 9223372036854770000}
+	encoded := EncodeSavedStarGiftListCursor(want.PinnedOrder, want.ID)
+	got, ok := DecodeSavedStarGiftListCursor(encoded)
+	if !ok || got != want {
+		t.Fatalf("cursor round trip = %+v ok=%v, want %+v", got, ok, want)
+	}
+
+	unpinned := SavedStarGiftListCursor{ID: 42}
+	got, ok = DecodeSavedStarGiftListCursor(EncodeSavedStarGiftListCursor(0, unpinned.ID))
+	if !ok || got != unpinned {
+		t.Fatalf("unpinned cursor round trip = %+v ok=%v, want %+v", got, ok, unpinned)
+	}
+}
+
+func TestSavedStarGiftListCursorRejectsInvalidAndSimpleIDShapes(t *testing.T) {
+	for _, cursor := range []string{
+		"not-base64!",
+		EncodeStarGiftCursor(42),
+		EncodeSavedStarGiftListCursor(-1, 42),
+		EncodeSavedStarGiftListCursor(1, 0),
+	} {
+		if got, ok := DecodeSavedStarGiftListCursor(cursor); ok {
+			t.Fatalf("cursor %q decoded as %+v, want rejected", cursor, got)
+		}
+	}
+}