fix: handle nullable types in @Query and @Param parsing

[Barba2k2]

📄 Description

Fixes the generated _parse<PType>() function to correctly handle nullable types (int?, double?, bool?). Previously, _parse<int?>('42') would fall through to the else branch and throw type 'String' is not a subtype of type 'int?' because int? != int in Dart's type system.

🔄 Changes Made

• Added _typeOf<T>() helper to the generated code for runtime nullable type comparison
• Extended _parse type checks to match both non-nullable and nullable variants (int and int?, double and double?, bool and bool?)

✅ Checklist

• Tests have been added or updated.
• Documentation has been updated (if necessary).
• Code review completed.

🔗 Related Issue

Resolves #93

[Copilot]

Pull request overview

This PR updates the backend generated vaden_application.dart runtime parsing helper to correctly parse nullable query/path/header parameter types (e.g., int?, double?, bool?) by adding a _typeOf<T>() helper and extending _parse<PType>() type checks to match both nullable and non-nullable variants.

Changes:

• Add _typeOf<T>() helper to enable runtime comparison against nullable types.
• Update _parse<PType>() to treat int?/double?/bool? the same as their non-nullable counterparts during parsing.

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[Copilot]

The nullable-type parsing behavior change here is not covered by a regression test. Since this affects generated request parsing for @Query/@param across all apps, please add a test that exercises a generated route/controller with int?/double?/bool? query/param values (including null and a valid value) to prevent regressions.

Suggested change

	return bool.parse(value) as PType;
	final lower = value.toLowerCase();
	if (lower == 'true') {
	return true as PType;
	} else if (lower == 'false') {
	return false as PType;
	}
	throw FormatException('Invalid bool: \$value');