feat(writer): add continue-on-error option for SQL writers

* Introduce ContinueOnError option to WriterOptions
* Update writer functions to support continue-on-error behavior
* Modify migration and database writing to handle continue-on-error

cmd/relspec/split.go

@@ -188,6 +188,7 @@ func runSplit(cmd *cobra.Command, args []string) error {
 		"",    // no schema filter for split
 		false, // no flatten-schema for split
 		splitNullableTypes,
+		false, // no continue-on-error for split
 	)
 	if err != nil {
 		return fmt.Errorf("failed to write output: %w", err)