Add SwiftUI Table demo and let container legend fill column width

SwiftUITableDemo exercises native SwiftUI Table accessibility on iPhone:
the parser does see accessibilityContainerType = .dataTable, but Table
collapses to a one-column List on iPhone and reports rowCount = 0,
columnCount = 0 with no UIAccessibilityContainerDataTableCell elements,
so the legend shows "Data Table (0 × 0)".

Container legend entries now expand to the full available width
(maxWidth: .infinity) so badges like "Data Table (0 × 0)" sit on a
single line instead of wrapping to fit the narrowest child.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: RoyalPineapple

Example/AccessibilitySnapshotPreviewsDemo/SwiftUITableDemo.swift

@@ -0,0 +1,43 @@
+import AccessibilitySnapshotPreviews
+import SwiftUI
+
+/// Spike: does native `SwiftUI.Table` emit `accessibilityContainerType = .dataTable`?
+/// Note: on iPhone, `Table` collapses to a single-column list; the accessibility tree
+/// may reflect that rather than a true data table.
+struct SwiftUITableDemo: View {
+    struct Sale: Identifiable {
+        let id = UUID()
+        let quarter: String
+        let revenue: String
+        let growth: String
+    }
+
+    private let sales: [Sale] = [
+        Sale(quarter: "Q1", revenue: "$10", growth: "+5%"),
+        Sale(quarter: "Q2", revenue: "$15", growth: "+50%"),
+        Sale(quarter: "Q3", revenue: "$12", growth: "-20%"),
+    ]
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 16) {
+            DemoSection(title: "SwiftUI Table", description: "native Table") {
+                Table(sales) {
+                    TableColumn("Quarter", value: \.quarter)
+                    TableColumn("Revenue", value: \.revenue)
+                    TableColumn("Growth", value: \.growth)
+                }
+                .frame(height: 220)
+            }
+
+            Spacer()
+        }
+        .padding()
+    }
+}
+
+#Preview {
+    SwiftUITableDemo()
+        .accessibilityPreview(
+            configuration: .init(viewRenderingMode: .drawHierarchyInRect, showContainers: true)
+        )
+}

Example/AccessibilitySnapshotPreviewsTests/ReferenceImages/_64/AccessibilitySnapshotPreviewsTests.SwiftUIRendererTests/testContainerDemo_26_4_402x874@3x.png

@@ -62,6 +62,13 @@ final class SwiftUIRendererTests: AccessibilitySnapshotPreviewsTestCase {
         )
     }
 
+    func testSwiftUITableDemo() {
+        snapshotVerifyAccessibility(
+            SwiftUITableDemo(),
+            configuration: .init(viewRenderingMode: .drawHierarchyInRect, showContainers: true)
+        )
+    }
+
     func testTabBarContainerDemo() {
         snapshotVerifyAccessibility(
             TabBarContainerDemo(),

Example/AccessibilitySnapshotPreviewsTests/ReferenceImages/_64/AccessibilitySnapshotPreviewsTests.SwiftUIRendererTests/testDataTableContainerDemo_26_4_402x874@3x.png

@@ -21,6 +21,7 @@ struct ContainerLegendEntryView: View {
             VStack(alignment: .leading, spacing: LegendLayoutMetrics.legendVerticalSpacing) {
                 childViews
             }
+            .frame(maxWidth: .infinity, alignment: .leading)
             .padding(Self.containerInset)
             .padding(.top, badgeHeight / 2)
             .overlay(