fix: Add context.Background() to sqlite.New() calls in test files

Multiple test files were still using the old sqlite.New(path) signature
instead of the new sqlite.New(ctx, path) signature. This was causing
compilation failures in the test suite.

Fixed files:
- internal/importer/importer_test.go
- internal/importer/external_ref_test.go
- internal/importer/timestamp_test.go
- internal/rpc/limits_test.go
- internal/rpc/list_filters_test.go
- internal/rpc/rpc_test.go
- internal/rpc/status_test.go
- internal/syncbranch/syncbranch_test.go

internal/syncbranch/syncbranch_test.go

@@ -50,7 +50,7 @@ func TestValidateBranchName(t *testing.T) {
 
 func newTestStore(t *testing.T) *sqlite.SQLiteStorage {
 	t.Helper()
-	store, err := sqlite.New("file::memory:?mode=memory&cache=private")
+	store, err := sqlite.New(context.Background(), "file::memory:?mode=memory&cache=private")
 	if err != nil {
 		t.Fatalf("Failed to create test database: %v", err)
 	}