feat(阶段1): 搬入 ojnext 为 apps/web，未改业务代码

apps/web/src/oj/learn/composables/useCodeHighlight.ts

@@ -0,0 +1,41 @@
+import hljs from "highlight.js/lib/core"
+import python from "highlight.js/lib/languages/python"
+import c from "highlight.js/lib/languages/c"
+
+hljs.registerLanguage("python", python)
+hljs.registerLanguage("c", c)
+
+export function escapeHtml(text: string): string {
+  return text.replace(/&/g, "&amp;").replace(/</g, "&lt;").replace(/>/g, "&gt;")
+}
+
+function normalizeLang(lang?: string): "python" | "c" | null {
+  return lang === "python" ? "python" : lang === "c" ? "c" : null
+}
+
+// 把整段代码高亮为 HTML；不支持的语言或异常时回退为转义文本
+export function highlight(code: string, lang?: string): string {
+  const language = normalizeLang(lang)
+  if (language) {
+    try {
+      return hljs.highlight(code, { language }).value
+    } catch {
+      // fall through
+    }
+  }
+  return escapeHtml(code)
+}
+
+// 按行高亮：整体高亮后再按行切分，保证跨行 token 着色正确，返回逐行 HTML 数组
+export function highlightLines(lines: string[], lang?: string): string[] {
+  const language = normalizeLang(lang)
+  if (language) {
+    try {
+      const html = hljs.highlight(lines.join("\n"), { language }).value
+      return html.split("\n")
+    } catch {
+      // fall through
+    }
+  }
+  return lines.map((line) => escapeHtml(line))
+}