feat: add immutable level template lifecycle

e2e/board.smoke.spec.ts

@@ -86,4 +86,20 @@ test('move, folder expansion, hand pan, pinch zoom, and reload persistence', asy
   await page.keyboard.up('Control')
   await expect.poll(() => board.getAttribute('style')).not.toEqual(transformBeforePinch)
   expect(await page.evaluate(() => ({ width: window.innerWidth, height: window.innerHeight, devicePixelRatio: window.devicePixelRatio }))).toEqual(browserMetricsBeforePinch)
+
+  page.once('dialog', dialog => dialog.accept('Browser Template'))
+  const templateSaved = page.waitForResponse(candidate => candidate.request().method() === 'POST' && candidate.url().includes('/templates?edit=1') && candidate.ok())
+  await page.getByRole('button', { name: 'SAVE TEMPLATE', exact: true }).click()
+  await templateSaved
+  await expect(page.locator('.terminal-status')).toContainText('VERSION 1')
+
+  let promptIndex = 0
+  const prompts = ['browser-template', 'Browser Template Clone']
+  const promptHandler = (dialog: { accept(promptText?: string): Promise<void> }) => dialog.accept(prompts[promptIndex++])
+  page.on('dialog', promptHandler)
+  await page.getByRole('button', { name: 'NEW FROM TEMPLATE', exact: true }).click()
+  await page.waitForURL(url => url.searchParams.get('level')?.startsWith('browser-template-') === true)
+  page.off('dialog', promptHandler)
+  await expect(page.getByRole('heading', { name: 'Browser Template Clone' })).toBeVisible()
+  await expect(page.getByRole('button', { name: 'Reset' })).toBeEnabled()
 })