Fix SwiftUI type-checker timeout in LoginView

Broke up complex expressions into computed properties and subviews to help the Swift compiler type-check the view hierarchy.

Changes:
- Extracted isFormValid computed property
- Extracted loginButtonContent as separate view
- Extracted loginButtonBackground with @ViewBuilder
- Simplified button disabled condition

This resolves "The compiler is unable to type-check this expression in reasonable time" error.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

iosApp/iosApp/Login/LoginView.swift

@@ -18,6 +18,22 @@ struct LoginView: View {
         case username, password
     }
 
+    // Computed properties to help type checker
+    private var isFormValid: Bool {
+        !viewModel.username.isEmpty && !viewModel.password.isEmpty
+    }
+
+    private var buttonBackgroundColor: Color {
+        if viewModel.isLoading || !isFormValid {
+            return AppColors.textTertiary
+        }
+        return .clear
+    }
+
+    private var shouldShowShadow: Bool {
+        isFormValid && !viewModel.isLoading
+    }
+
     var body: some View {
         NavigationView {
             ZStack {
@@ -172,31 +188,9 @@ struct LoginView: View {
 
                             // Login Button
                             Button(action: viewModel.login) {
-                                HStack(spacing: AppSpacing.sm) {
-                                    if viewModel.isLoading {
-                                        ProgressView()
-                                            .progressViewStyle(CircularProgressViewStyle(tint: .white))
-                                    }
-                                    Text(viewModel.isLoading ? "Signing In..." : "Sign In")
-                                        .font(AppTypography.titleSmall)
-                                        .fontWeight(.semibold)
-                                }
-                                .frame(maxWidth: .infinity)
-                                .frame(height: 56)
-                                .foregroundColor(.white)
-                                .background(
-                                    viewModel.isLoading || viewModel.username.isEmpty || viewModel.password.isEmpty
-                                        ? AppColors.textTertiary
-                                        : AppColors.primaryGradient
-                                )
-                                .cornerRadius(AppRadius.md)
-                                .shadow(
-                                    color: viewModel.username.isEmpty || viewModel.password.isEmpty ? .clear : AppColors.primary.opacity(0.3),
-                                    radius: 10,
-                                    y: 5
-                                )
+                                loginButtonContent
                             }
-                            .disabled(viewModel.isLoading || viewModel.username.isEmpty || viewModel.password.isEmpty)
+                            .disabled(!isFormValid || viewModel.isLoading)
 
                             // Sign Up Link
                             HStack(spacing: AppSpacing.xs) {
@@ -273,6 +267,38 @@ struct LoginView: View {
             }
         }
     }
+
+    // MARK: - Subviews
+    private var loginButtonContent: some View {
+        HStack(spacing: AppSpacing.sm) {
+            if viewModel.isLoading {
+                ProgressView()
+                    .progressViewStyle(CircularProgressViewStyle(tint: .white))
+            }
+            Text(viewModel.isLoading ? "Signing In..." : "Sign In")
+                .font(AppTypography.titleSmall)
+                .fontWeight(.semibold)
+        }
+        .frame(maxWidth: .infinity)
+        .frame(height: 56)
+        .foregroundColor(.white)
+        .background(loginButtonBackground)
+        .cornerRadius(AppRadius.md)
+        .shadow(
+            color: shouldShowShadow ? AppColors.primary.opacity(0.3) : .clear,
+            radius: 10,
+            y: 5
+        )
+    }
+
+    @ViewBuilder
+    private var loginButtonBackground: some View {
+        if viewModel.isLoading || !isFormValid {
+            AppColors.textTertiary
+        } else {
+            AppColors.primaryGradient
+        }
+    }
 }
 
 // MARK: - Preview