fix(render): highlight quill code blocks and fix light-theme contrast

- highlightHtmlCode only queried pre, but Quill v2 code blocks are
  div.ql-code-block-container > div.ql-code-block, so they never got
  highlighted; convert them to pre > code.hljs like markdown blocks
- light theme inherited github-dark's near-white base color on a light
  background; force a dark code block background in light mode

src/assets/markdown-override.css

@@ -83,6 +83,17 @@
   word-break: normal;
 }
 
+/* 浅色主题：代码块固定深色底（与编辑器内深色代码块一致），保证 github-dark 配色可读 */
+.markdown-body:not(.markdown-body-dark) pre {
+  background-color: #151b23;
+  color: #e6edf3;
+  border: 1px solid #3d444d;
+}
+
+.markdown-body:not(.markdown-body-dark) pre code {
+  color: #e6edf3;
+}
+
 .markdown-body.markdown-body-dark .ql-code-block-container {
   background-color: #151b23;
   border-color: #3d444d;

src/utils/markdown.ts

@@ -16,24 +16,41 @@ marked.use(
   })
 )
 
+function highlightCode(code: string, lang: string): string {
+  if (lang && hljs.getLanguage(lang)) {
+    return hljs.highlight(code, { language: lang }).value
+  }
+  return hljs.highlightAuto(code).value
+}
+
 function highlightHtmlCode(html: string): string {
   const doc = new DOMParser().parseFromString(html, 'text/html')
-  const blocks = Array.from(doc.querySelectorAll<HTMLElement>('pre'))
-  for (const pre of blocks) {
-    const container = pre.closest<HTMLElement>('.ql-code-block-container')
-    const codeEl = pre.querySelector<HTMLElement>('code')
+  const blocks = Array.from(doc.querySelectorAll<HTMLElement>('pre, .ql-code-block-container'))
+
+  for (const block of blocks) {
+    if (block.classList.contains('ql-code-block-container')) {
+      const lines = Array.from(block.querySelectorAll<HTMLElement>('.ql-code-block'))
+      const text = lines.map((el) => el.textContent ?? '').join('\n').replace(/\n$/, '')
+      const lang = block.getAttribute('data-language') ?? ''
+      const pre = doc.createElement('pre')
+      pre.className = 'hljs'
+      const code = doc.createElement('code')
+      code.className = lang ? `hljs language-${lang}` : 'hljs'
+      code.innerHTML = highlightCode(text, lang)
+      pre.appendChild(code)
+      block.replaceWith(pre)
+      continue
+    }
+
+    const container = block.closest<HTMLElement>('.ql-code-block-container')
+    const codeEl = block.querySelector<HTMLElement>('code')
     let lang = container?.getAttribute('data-language') ?? ''
     if (!lang && codeEl) {
       const m = (codeEl.className || '').match(/language-([\w-]+)/)
       if (m) lang = m[1]
     }
-    const text = codeEl ? codeEl.textContent ?? '' : pre.textContent ?? ''
-    let highlighted: string
-    if (lang && hljs.getLanguage(lang)) {
-      highlighted = hljs.highlight(text, { language: lang }).value
-    } else {
-      highlighted = hljs.highlightAuto(text).value
-    }
+    const text = codeEl ? codeEl.textContent ?? '' : block.textContent ?? ''
+    const highlighted = highlightCode(text, lang)
     if (codeEl) {
       codeEl.innerHTML = highlighted
       codeEl.classList.add('hljs')
@@ -41,8 +58,8 @@ function highlightHtmlCode(html: string): string {
       const newCode = doc.createElement('code')
       newCode.className = 'hljs'
       newCode.innerHTML = highlighted
-      pre.innerHTML = ''
-      pre.appendChild(newCode)
+      block.innerHTML = ''
+      block.appendChild(newCode)
     }
   }
   return doc.body.innerHTML