fix: collect imports for enums in separate files

[Barba2k2]

Summary

• Fixes [BUG] Vaden não importa enums no código gerado pelo Build Runner #152 — enums defined in separate files were not imported in the generated vaden_application.dart, causing Undefined name compilation errors
• Added type import collection for DTO fields and controller method parameters in vaden_class_scanner
• Handles enums, List<Enum>, Future<Enum>, and inherited method parameters

Changes Made

• vaden_class_scanner/lib/src/setups/initial.dart: Added _collectFieldTypeImports, _collectMethodParamTypeImports, and _addTypeImport helpers that resolve library URIs for non-core types referenced by DTO fields and controller parameters. Integrated into _selectComponent for DTO and Controller processing.
• vaden/example/: Added reproduction test cases with enums in separate files (ProductCategory, OrderStatus), DTOs using them (ProductDto, OrderDto), and a controller (OrderController).

Root Cause

_checkMasterAnnotations only discovers classes with Vaden annotations (@DTO, @Controller, etc.). Plain enums in separate files are never scanned, so their import URIs are never added to the generated output. The fix collects imports by inspecting the actual types referenced in fields and method parameters.

Checklist

• Tests have been added or updated.
• Code review completed.

Related Issue

Resolves #152