fix(wasm): radio groups no longer merge into one

Bump wxwidgets to the %p->%zu radio-group name fix and add a standalone
wxWidgets harness plus an e2e regression that asserts three radio groups
in one window select independently. Build artifacts are gitignored; only
radiogroups_test.cpp is tracked.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tests/e2e/radiogroups.spec.ts

@@ -0,0 +1,81 @@
+// wxRadioButton group exclusivity tests.
+//
+// Regression coverage for the WASM DOM-port bug where every wxRadioButton got
+// the same HTML `name` ("wxrb-", because `%p` rendered empty in wxString::Format),
+// collapsing all radio groups in a window into one. The harness lays out three
+// independent groups, each pre-selecting a different column, so a correct build
+// keeps three distinct group `name`s with exactly one checked radio per group.
+import { test, expect, tryLoadApp } from './utils/fixtures';
+
+const URL = '/standalone/radiogroups/radiogroups_test.html';
+
+// Collect, per HTML radio group `name`, how many radios it has and how many are checked.
+async function readGroups(page: import('@playwright/test').Page) {
+  return page.evaluate(() => {
+    const radios = Array.from(
+      document.querySelectorAll<HTMLInputElement>('input[type=radio]')
+    ).filter(r => r.offsetParent !== null); // visible only
+
+    const byName: Record<string, { total: number; checked: number }> = {};
+    for (const r of radios) {
+      (byName[r.name] ??= { total: 0, checked: 0 }).total++;
+      if (r.checked) byName[r.name].checked++;
+    }
+    return {
+      radioCount: radios.length,
+      distinctNames: Array.from(new Set(radios.map(r => r.name))),
+      byName,
+      totalChecked: radios.filter(r => r.checked).length,
+      details: radios.map((r, i) => ({ i, name: r.name, checked: r.checked })),
+    };
+  });
+}
+
+test.describe('wxRadioButton groups', () => {
+  test('radio groups app loads without errors', async ({ page, testLogger }) => {
+    await page.goto(URL);
+    const loaded = await tryLoadApp(page);
+    await page.screenshot({ path: 'test-results/radiogroups-01-loaded.png', fullPage: true });
+    expect(loaded, 'radio groups app should load').toBe(true);
+    expect(testLogger.errors.filter(e => !e.includes('favicon'))).toHaveLength(0);
+  });
+
+  test('selecting in one group does not disturb the others', async ({ page }) => {
+    await page.goto(URL);
+    expect(await tryLoadApp(page), 'app should load').toBe(true);
+
+    // 3 groups x 4 columns = 12 radios.
+    await page.waitForFunction(
+      () => document.querySelectorAll('input[type=radio]').length >= 12,
+      undefined,
+      { timeout: 10_000 }
+    );
+
+    // Structural proof of the fix: three separate HTML exclusivity groups, not
+    // one merged group. (Pre-fix every radio shares name "wxrb-" => length 1.)
+    const before = await readGroups(page);
+    expect(before.radioCount, 'should render 3 groups x 4 columns').toBe(12);
+    expect(before.distinctNames,
+      `expected 3 group names, got ${JSON.stringify(before.distinctNames)}`).toHaveLength(3);
+
+    // Behavioural proof: click one radio in each group, on a different column.
+    // Groups are contiguous in DOM order: A=0..3, B=4..7, C=8..11.
+    const radios = page.locator('input[type=radio]');
+    await radios.nth(1).click();  // Group A, Ctrl
+    await radios.nth(6).click();  // Group B, Shift
+    await radios.nth(11).click(); // Group C, Alt
+    await page.waitForTimeout(100);
+
+    const after = await readGroups(page);
+    await page.screenshot({ path: 'test-results/radiogroups-02-selections.png', fullPage: true });
+
+    // Each group keeps exactly its own selection. Pre-fix, the three clicks land
+    // in one merged group so only the last survives => totalChecked === 1.
+    expect(after.totalChecked, 'one selection per group => 3 total').toBe(3);
+    for (const [name, counts] of Object.entries(after.byName)) {
+      expect(counts.checked, `group ${name} should keep exactly one checked`).toBe(1);
+    }
+    // Spot-check the exact radios we clicked are the ones checked.
+    expect(after.details.filter(d => d.checked).map(d => d.i)).toEqual([1, 6, 11]);
+  });
+});