Fix: Resolve Swift 6 Equatable conformance errors for View types

Add explicit nonisolated == implementations using MainActor.assumeIsolated
for all View types with @preconcurrency Equatable conformances:

- Box
- Card
- ContainerView
- _ContainerViewCore
- Dialog
- Panel
- ProgressView
- VStack, HStack, ZStack

This fixes CI failures on macOS where the derived Equatable conformance
cannot access @MainActor-isolated properties from nonisolated context.

Sources/TUIkit/Views/Box.swift

@@ -164,4 +164,12 @@ struct BufferView: View, Renderable {
 
 // MARK: - Equatable Conformance
 
-extension Box: @preconcurrency Equatable where Content: Equatable {}
+extension Box: Equatable where Content: Equatable {
+    nonisolated public static func == (lhs: Box<Content>, rhs: Box<Content>) -> Bool {
+        MainActor.assumeIsolated {
+            lhs.content == rhs.content &&
+            lhs.borderStyle == rhs.borderStyle &&
+            lhs.borderColor == rhs.borderColor
+        }
+    }
+}

Sources/TUIkit/Views/Card.swift

@@ -127,7 +127,17 @@ public struct Card<Content: View, Footer: View>: View {
 
 // MARK: - Equatable Conformance
 
-extension Card: @preconcurrency Equatable where Content: Equatable, Footer: Equatable {}
+extension Card: Equatable where Content: Equatable, Footer: Equatable {
+    nonisolated public static func == (lhs: Card<Content, Footer>, rhs: Card<Content, Footer>) -> Bool {
+        MainActor.assumeIsolated {
+            lhs.title == rhs.title &&
+            lhs.content == rhs.content &&
+            lhs.footer == rhs.footer &&
+            lhs.config == rhs.config &&
+            lhs.backgroundColor == rhs.backgroundColor
+        }
+    }
+}
 
 // MARK: - Rendering
 

Sources/TUIkit/Views/ContainerView.swift

@@ -246,7 +246,18 @@ struct ContainerView<Content: View, Footer: View>: View {
 
 // MARK: - Equatable Conformance
 
-extension ContainerView: @preconcurrency Equatable where Content: Equatable, Footer: Equatable {}
+extension ContainerView: Equatable where Content: Equatable, Footer: Equatable {
+    nonisolated static func == (lhs: ContainerView<Content, Footer>, rhs: ContainerView<Content, Footer>) -> Bool {
+        MainActor.assumeIsolated {
+            lhs.title == rhs.title &&
+            lhs.titleColor == rhs.titleColor &&
+            lhs.content == rhs.content &&
+            lhs.footer == rhs.footer &&
+            lhs.style == rhs.style &&
+            lhs.padding == rhs.padding
+        }
+    }
+}
 
 // MARK: - Convenience Initializer (no footer)
 
@@ -463,4 +474,15 @@ private struct _ContainerViewCore<Content: View, Footer: View>: View, Renderable
 
 // MARK: - Equatable Conformance
 
-extension _ContainerViewCore: @preconcurrency Equatable where Content: Equatable, Footer: Equatable {}
+extension _ContainerViewCore: Equatable where Content: Equatable, Footer: Equatable {
+    nonisolated static func == (lhs: _ContainerViewCore<Content, Footer>, rhs: _ContainerViewCore<Content, Footer>) -> Bool {
+        MainActor.assumeIsolated {
+            lhs.title == rhs.title &&
+            lhs.titleColor == rhs.titleColor &&
+            lhs.content == rhs.content &&
+            lhs.footer == rhs.footer &&
+            lhs.style == rhs.style &&
+            lhs.padding == rhs.padding
+        }
+    }
+}

Sources/TUIkit/Views/Dialog.swift

@@ -102,7 +102,16 @@ public struct Dialog<Content: View, Footer: View>: View {
 
 // MARK: - Equatable Conformance
 
-extension Dialog: @preconcurrency Equatable where Content: Equatable, Footer: Equatable {}
+extension Dialog: Equatable where Content: Equatable, Footer: Equatable {
+    nonisolated public static func == (lhs: Dialog<Content, Footer>, rhs: Dialog<Content, Footer>) -> Bool {
+        MainActor.assumeIsolated {
+            lhs.title == rhs.title &&
+            lhs.content == rhs.content &&
+            lhs.footer == rhs.footer &&
+            lhs.config == rhs.config
+        }
+    }
+}
 
 // MARK: - Rendering
 

Sources/TUIkit/Views/Panel.swift

@@ -122,7 +122,16 @@ public struct Panel<Content: View, Footer: View>: View {
 
 // MARK: - Equatable Conformance
 
-extension Panel: @preconcurrency Equatable where Content: Equatable, Footer: Equatable {}
+extension Panel: Equatable where Content: Equatable, Footer: Equatable {
+    nonisolated public static func == (lhs: Panel<Content, Footer>, rhs: Panel<Content, Footer>) -> Bool {
+        MainActor.assumeIsolated {
+            lhs.title == rhs.title &&
+            lhs.content == rhs.content &&
+            lhs.footer == rhs.footer &&
+            lhs.config == rhs.config
+        }
+    }
+}
 
 // MARK: - Convenience Initializer (no footer)
 

Sources/TUIkit/Views/ProgressView.swift

@@ -227,7 +227,16 @@ extension ProgressView {
 
 // MARK: - Equatable Conformance
 
-extension ProgressView: @preconcurrency Equatable where Label: Equatable, CurrentValueLabel: Equatable {}
+extension ProgressView: Equatable where Label: Equatable, CurrentValueLabel: Equatable {
+    nonisolated public static func == (lhs: ProgressView<Label, CurrentValueLabel>, rhs: ProgressView<Label, CurrentValueLabel>) -> Bool {
+        MainActor.assumeIsolated {
+            lhs.fractionCompleted == rhs.fractionCompleted &&
+            lhs.style == rhs.style &&
+            lhs.label == rhs.label &&
+            lhs.currentValueLabel == rhs.currentValueLabel
+        }
+    }
+}
 
 // MARK: - Rendering
 

Sources/TUIkit/Views/Stacks.swift

@@ -230,9 +230,34 @@ public struct Alignment: Sendable, Equatable {
 
 // MARK: - Equatable Conformances
 
-extension VStack: @preconcurrency Equatable where Content: Equatable {}
-extension HStack: @preconcurrency Equatable where Content: Equatable {}
-extension ZStack: @preconcurrency Equatable where Content: Equatable {}
+extension VStack: Equatable where Content: Equatable {
+    nonisolated public static func == (lhs: VStack<Content>, rhs: VStack<Content>) -> Bool {
+        MainActor.assumeIsolated {
+            lhs.alignment == rhs.alignment &&
+            lhs.spacing == rhs.spacing &&
+            lhs.content == rhs.content
+        }
+    }
+}
+
+extension HStack: Equatable where Content: Equatable {
+    nonisolated public static func == (lhs: HStack<Content>, rhs: HStack<Content>) -> Bool {
+        MainActor.assumeIsolated {
+            lhs.alignment == rhs.alignment &&
+            lhs.spacing == rhs.spacing &&
+            lhs.content == rhs.content
+        }
+    }
+}
+
+extension ZStack: Equatable where Content: Equatable {
+    nonisolated public static func == (lhs: ZStack<Content>, rhs: ZStack<Content>) -> Bool {
+        MainActor.assumeIsolated {
+            lhs.alignment == rhs.alignment &&
+            lhs.content == rhs.content
+        }
+    }
+}
 
 // MARK: - VStack Rendering