feat(csv-loader): expand custom type references in schemas

Allow custom type names to be expanded before parsing the schema
string. This enables using declared types within complex structures
like tuples or arrays. The original schema string is preserved for
type generation to ensure the output uses the named type rather than
the expanded inline definition.

src/csv-loader/loader.ts

@@ -209,11 +209,21 @@ export function parseCsv(
       // Check if schema string matches a declared type name
       let schema: Schema;
       let declaredTypeName: string | undefined;
+      let columnSchemaString: string | undefined;
       if (declaredTypes.has(schemaString)) {
         schema = declaredTypes.get(schemaString)!;
         declaredTypeName = schemaString;
       } else {
-        schema = parseSchema(schemaString);
+        // Expand any custom type name references before parsing
+        const expandedSchema = expandSchemaString(
+          schemaString,
+          declaredSchemaStrings,
+        );
+        schema = parseSchema(expandedSchema.trim());
+        // Only preserve the original schema string if expansion actually changed it
+        if (expandedSchema !== schemaString) {
+          columnSchemaString = schemaString;
+        }
       }
 
       const config: PropertyConfig = {
@@ -222,6 +232,7 @@ export function parseCsv(
         validator: createValidator(schema),
         parser: (valueString: string) => parseValue(schema, valueString),
         declaredTypeName,
+        schemaString: columnSchemaString,
       };
 
       if (schema.type === "reference") {