Sync inserted AI regions immediately

- Track report editor AI regions in React state instead of only scanning contentEditable DOM during render.

- Observe editor AI region mutations and refresh the AI writing target dropdown without requiring page navigation or refresh.

- Select newly inserted AI regions immediately after insertion and keep a live DOM fallback for generation.

- Harden AI region insertion so it still appends the region if execCommand has no active editor selection.

- Escape AI region names before injecting template HTML and add an accessible label for the insert button.

- Add Playwright coverage for inserting an AI region and seeing it immediately in the AI writing dropdown.

- Update report editor, feature, progress, testing, and AGENTS documentation for AI region synchronization.

e2e/report-ai-region.spec.ts

@@ -0,0 +1,25 @@
+import { expect, test } from '@playwright/test';
+import { loginByApi, uniqueId } from './helpers';
+
+test('newly inserted AI region appears in the AI writing target dropdown immediately', async ({ page }) => {
+  await loginByApi(page, '0001');
+  const regionName = `AI区域${uniqueId('region')}`;
+
+  page.on('dialog', async (dialog) => {
+    if (dialog.type() === 'prompt') {
+      await dialog.accept(regionName);
+      return;
+    }
+    await dialog.accept();
+  });
+
+  await page.goto('/report-editor');
+  await page.getByTitle('插入AI可编辑区域').click();
+  await page.getByRole('button', { name: 'AI撰写' }).click();
+
+  const aiRegionSelect = page.locator('select').filter({
+    has: page.locator('option', { hasText: regionName }),
+  });
+  await expect(aiRegionSelect).toHaveValue(regionName);
+  await expect(page.locator('select option', { hasText: regionName })).toHaveCount(1);
+});