fix: resolve rebase conflict with #252 vegan field

Keep isVegan field name from this PR but preserve the robust multi-type
parsing (bool/num/string) introduced by #252. Remove the duplicate fragile
cast and rename all .vegan accessor references to .isVegan.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: richardthe3rd

lib/models/drink.dart

@@ -62,7 +62,6 @@ class Product {
   final String? notes;
   final String? statusText;
   final String? bar;
-  final bool? vegan;
   final Map<String, int> allergens;
   final bool? isVegan;
 
@@ -76,7 +75,6 @@ class Product {
     this.notes,
     this.statusText,
     this.bar,
-    this.vegan,
     this.allergens = const {},
     this.isVegan,
   });
@@ -148,9 +146,8 @@ class Product {
       notes: json['notes']?.toString(),
       statusText: json['status_text']?.toString(),
       bar: bar,
-      vegan: parsedVegan,
       allergens: allergens,
-      isVegan: json['is_vegan'] as bool?,
+      isVegan: parsedVegan,
     );
   }
 
@@ -165,7 +162,6 @@ class Product {
       if (notes != null) 'notes': notes,
       if (statusText != null) 'status_text': statusText,
       if (bar != null) 'bar': bar,
-      if (vegan != null) 'is_vegan': vegan,
       'allergens': allergens,
       if (isVegan != null) 'is_vegan': isVegan,
     };
@@ -260,7 +256,6 @@ class Drink {
   String? get notes => product.notes;
   String? get statusText => product.statusText;
   String? get bar => product.bar;
-  bool? get vegan => product.vegan;
   Map<String, int> get allergens => product.allergens;
   AvailabilityStatus? get availabilityStatus => product.availabilityStatus;
   String? get allergenText => product.allergenText;

lib/screens/drink_detail_screen.dart

@@ -179,7 +179,7 @@ class _DrinkDetailScreenState extends State<DrinkDetailScreen> {
                 : theme.colorScheme.primary,
           ),
         // Vegan indicator
-        if (drink.vegan == true)
+        if (drink.isVegan == true)
           HeroInfoRow(
             icon: Icons.eco,
             text: 'Vegan',

test/drink_detail_screen_test.dart

@@ -40,7 +40,7 @@ void main() {
       dispense: 'cask',
       style: 'IPA',
       bar: 'Main Bar',
-      vegan: true,
+      isVegan: true,
       notes: 'A hoppy beer with citrus notes',
       allergens: {'gluten': 1, 'sulphites': 1},
     );

test/models_test.dart

@@ -29,7 +29,7 @@ void main() {
       expect(product.notes, 'A test beer');
       expect(product.statusText, 'Plenty left');
       expect(product.bar, 'Main Bar');
-      expect(product.vegan, isTrue);
+      expect(product.isVegan, isTrue);
       expect(product.allergens, {'gluten': 1});
     });
 
@@ -48,7 +48,7 @@ void main() {
       expect(product.notes, isNull);
       expect(product.statusText, isNull);
       expect(product.bar, isNull);
-      expect(product.vegan, isNull);
+      expect(product.isVegan, isNull);
       expect(product.allergens, isEmpty);
     });
 
@@ -198,7 +198,7 @@ void main() {
           'abv': '4.0',
           'vegan': true,
         });
-        expect(product.vegan, isTrue);
+        expect(product.isVegan, isTrue);
       });
 
       test('prefers is_vegan when both keys are present', () {
@@ -211,7 +211,7 @@ void main() {
           'is_vegan': false,
           'vegan': true,
         });
-        expect(product.vegan, isFalse);
+        expect(product.isVegan, isFalse);
       });
 
       test('parses numeric one as true', () {
@@ -223,7 +223,7 @@ void main() {
           'abv': '4.0',
           'is_vegan': 1,
         });
-        expect(product.vegan, isTrue);
+        expect(product.isVegan, isTrue);
       });
 
       test('parses numeric zero as false', () {
@@ -235,7 +235,7 @@ void main() {
           'abv': '4.0',
           'is_vegan': 0,
         });
-        expect(product.vegan, isFalse);
+        expect(product.isVegan, isFalse);
       });
 
       test('parses supported string values', () {
@@ -287,12 +287,12 @@ void main() {
           'abv': '4.0',
           'is_vegan': '0',
         });
-        expect(yesProduct.vegan, isTrue);
-        expect(noProduct.vegan, isFalse);
-        expect(trueProduct.vegan, isTrue);
-        expect(falseProduct.vegan, isFalse);
-        expect(oneProduct.vegan, isTrue);
-        expect(zeroProduct.vegan, isFalse);
+        expect(yesProduct.isVegan, isTrue);
+        expect(noProduct.isVegan, isFalse);
+        expect(trueProduct.isVegan, isTrue);
+        expect(falseProduct.isVegan, isFalse);
+        expect(oneProduct.isVegan, isTrue);
+        expect(zeroProduct.isVegan, isFalse);
       });
 
       test('returns null for unsupported string values', () {
@@ -304,7 +304,7 @@ void main() {
           'abv': '4.0',
           'is_vegan': 'maybe',
         });
-        expect(product.vegan, isNull);
+        expect(product.isVegan, isNull);
       });
     });
 
@@ -433,7 +433,7 @@ void main() {
           notes: 'A test beer',
           statusText: 'Plenty left',
           bar: 'Main Bar',
-          vegan: true,
+          isVegan: true,
           allergens: {'gluten': 1},
         );
 
@@ -828,7 +828,7 @@ void main() {
       expect(drink.notes, 'Hoppy and bold');
       expect(drink.statusText, 'Plenty left');
       expect(drink.bar, 'Bar A');
-      expect(drink.vegan, isTrue);
+      expect(drink.isVegan, isTrue);
       expect(drink.allergens, {'gluten': 1});
       expect(drink.availabilityStatus, AvailabilityStatus.plenty);
       expect(drink.allergenText, 'Gluten');