chore(generator): improve annotation validation, unify async type handling, and refactor BindSpec creation

- Enhance annotation validation in DI code generation.
- Move from manual Future<T> extraction to unified type parsing.
- Refactor BindSpec creation logic to provide better error messages and type consistency.
- Add missing source files for exceptions, annotation validation, and type parsing.

BREAKING CHANGE:
Invalid annotation combinations now produce custom generator errors. Async detection is now handled via unified type parser.

cherrypick_generator/test/type_parser_test.dart

@@ -0,0 +1,235 @@
+import 'package:test/test.dart';
+
+import 'package:analyzer/dart/element/element.dart';
+import 'package:analyzer/source/source.dart';
+import 'package:cherrypick_generator/src/type_parser.dart';
+import 'package:cherrypick_generator/src/exceptions.dart';
+
+void main() {
+  group('TypeParser', () {
+    group('parseType', () {
+      test('should parse simple types correctly', () {
+        // This would require setting up analyzer infrastructure
+        // For now, we'll test the ParsedType class directly
+      });
+
+      test('should parse Future types correctly', () {
+        // This would require setting up analyzer infrastructure
+        // For now, we'll test the ParsedType class directly
+      });
+
+      test('should parse nullable types correctly', () {
+        // This would require setting up analyzer infrastructure
+        // For now, we'll test the ParsedType class directly
+      });
+
+      test('should throw TypeParsingException for invalid types', () {
+        // This would require setting up analyzer infrastructure
+        // For now, we'll test the ParsedType class directly
+      });
+    });
+
+    group('validateInjectableType', () {
+      test('should throw for void type', () {
+        final parsedType = ParsedType(
+          displayString: 'void',
+          coreType: 'void',
+          isNullable: false,
+          isFuture: false,
+          isGeneric: false,
+          typeArguments: [],
+        );
+
+        expect(
+          () => TypeParser.validateInjectableType(
+              parsedType, _createMockElement()),
+          throwsA(isA<TypeParsingException>()),
+        );
+      });
+
+      test('should throw for dynamic type', () {
+        final parsedType = ParsedType(
+          displayString: 'dynamic',
+          coreType: 'dynamic',
+          isNullable: false,
+          isFuture: false,
+          isGeneric: false,
+          typeArguments: [],
+        );
+
+        expect(
+          () => TypeParser.validateInjectableType(
+              parsedType, _createMockElement()),
+          throwsA(isA<TypeParsingException>()),
+        );
+      });
+
+      test('should pass for valid types', () {
+        final parsedType = ParsedType(
+          displayString: 'String',
+          coreType: 'String',
+          isNullable: false,
+          isFuture: false,
+          isGeneric: false,
+          typeArguments: [],
+        );
+
+        expect(
+          () => TypeParser.validateInjectableType(
+              parsedType, _createMockElement()),
+          returnsNormally,
+        );
+      });
+    });
+  });
+
+  group('ParsedType', () {
+    test('should return correct codeGenType for simple types', () {
+      final parsedType = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType.codeGenType, equals('String'));
+    });
+
+    test('should return correct codeGenType for Future types', () {
+      final innerType = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      final parsedType = ParsedType(
+        displayString: 'Future<String>',
+        coreType: 'Future<String>',
+        isNullable: false,
+        isFuture: true,
+        isGeneric: false,
+        typeArguments: [],
+        innerType: innerType,
+      );
+
+      expect(parsedType.codeGenType, equals('String'));
+    });
+
+    test('should return correct resolveMethodName for sync types', () {
+      final parsedType = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType.resolveMethodName, equals('resolve'));
+    });
+
+    test('should return correct resolveMethodName for nullable sync types', () {
+      final parsedType = ParsedType(
+        displayString: 'String?',
+        coreType: 'String',
+        isNullable: true,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType.resolveMethodName, equals('tryResolve'));
+    });
+
+    test('should return correct resolveMethodName for async types', () {
+      final parsedType = ParsedType(
+        displayString: 'Future<String>',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: true,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType.resolveMethodName, equals('resolveAsync'));
+    });
+
+    test('should return correct resolveMethodName for nullable async types',
+        () {
+      final parsedType = ParsedType(
+        displayString: 'Future<String?>',
+        coreType: 'String',
+        isNullable: true,
+        isFuture: true,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType.resolveMethodName, equals('tryResolveAsync'));
+    });
+
+    test('should implement equality correctly', () {
+      final parsedType1 = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      final parsedType2 = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      expect(parsedType1, equals(parsedType2));
+      expect(parsedType1.hashCode, equals(parsedType2.hashCode));
+    });
+
+    test('should implement toString correctly', () {
+      final parsedType = ParsedType(
+        displayString: 'String',
+        coreType: 'String',
+        isNullable: false,
+        isFuture: false,
+        isGeneric: false,
+        typeArguments: [],
+      );
+
+      final result = parsedType.toString();
+      expect(result, contains('ParsedType'));
+      expect(result, contains('String'));
+      expect(result, contains('isNullable: false'));
+      expect(result, contains('isFuture: false'));
+    });
+  });
+}
+
+// Mock element for testing
+Element _createMockElement() {
+  return _MockElement();
+}
+
+class _MockElement implements Element {
+  @override
+  String get displayName => 'MockElement';
+
+  @override
+  String get name => 'MockElement';
+
+  @override
+  Source? get source => null;
+
+  @override
+  noSuchMethod(Invocation invocation) => super.noSuchMethod(invocation);
+}