fix(learning): load readme images over https

tests/unit/learning-page.test.tsx

@@ -17,7 +17,9 @@ vi.mock('@/lib/learning', () => ({
 }));
 
 vi.mock('@/pages/Learning/ProjectImage', () => ({
-  ProjectImage: ({ src, alt }: { src: string; alt: string }) => <img src={src} alt={alt} />,
+  ProjectImage: ({ src, alt, allowHttps }: { src: string; alt: string; allowHttps?: boolean }) => (
+    <img src={src} alt={alt} data-allow-https={allowHttps ? 'true' : 'false'} />
+  ),
 }));
 
 const project = {
@@ -74,12 +76,12 @@ describe('Learning project pages', () => {
     expect(fetchLearningProjectsMock).toHaveBeenNthCalledWith(2, { cursor: 'cursor-2', limit: 24 });
   });
 
-  it('renders Markdown without raw HTML and keeps remote README media on the controlled path', async () => {
+  it('renders Markdown without raw HTML and allows direct HTTPS README images', async () => {
     fetchLearningProjectMock.mockResolvedValue({
       ...project,
       archiveFileName: 'robot-arm.zip',
       archiveSha256: 'a'.repeat(64),
-      readmeMarkdown: '# 开始搭建\n\n![接线图](/api/learning/projects/robot-arm/media/wiring)\n\n<script>bad()</script>\n\n[参考资料](https://example.com/guide)',
+      readmeMarkdown: '# 开始搭建\n\n![接线图](https://images.example.com/wiring.svg)\n\n<script>bad()</script>\n\n[参考资料](https://example.com/guide)',
     });
     render(
       <MemoryRouter initialEntries={['/learning/project/robot-arm']}>
@@ -90,8 +92,9 @@ describe('Learning project pages', () => {
     expect(await screen.findByRole('heading', { name: '开始搭建' })).toBeInTheDocument();
     expect(screen.getByAltText('接线图')).toHaveAttribute(
       'src',
-      '/api/learning/projects/robot-arm/media/wiring',
+      'https://images.example.com/wiring.svg',
     );
+    expect(screen.getByAltText('接线图')).toHaveAttribute('data-allow-https', 'true');
     expect(document.querySelector('script')).toBeNull();
     fireEvent.click(screen.getByRole('link', { name: '参考资料' }));
     expect(openLearningExternalLinkMock).toHaveBeenCalledWith('https://example.com/guide');