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/importer/timestamp_test.go

@@ -18,7 +18,7 @@ func TestImportTimestampPrecedence(t *testing.T) {
 	dbPath := filepath.Join(tmpDir, "test.db")
 	
 	// Initialize storage
-	store, err := sqlite.New(dbPath)
+	store, err := sqlite.New(context.Background(), dbPath)
 	if err != nil {
 		t.Fatalf("Failed to create storage: %v", err)
 	}
@@ -138,7 +138,7 @@ func TestImportSameTimestamp(t *testing.T) {
 	tmpDir := t.TempDir()
 	dbPath := filepath.Join(tmpDir, "test.db")
 	
-	store, err := sqlite.New(dbPath)
+	store, err := sqlite.New(context.Background(), dbPath)
 	if err != nil {
 		t.Fatalf("Failed to create storage: %v", err)
 	}