feat: add danmaku XML parser and color util

utils/danmaku.ts

@@ -0,0 +1,24 @@
+import type { DanmakuItem } from '../services/types';
+
+export function parseDanmakuXml(xml: string): DanmakuItem[] {
+  const re = /<d p="([^"]+)">([^<]*)<\/d>/g;
+  const items: DanmakuItem[] = [];
+  let m: RegExpExecArray | null;
+  while ((m = re.exec(xml)) !== null) {
+    const p = m[1].split(',');
+    if (p.length < 4) continue;
+    const time = parseFloat(p[0]);
+    const mode = parseInt(p[1], 10);
+    const text = m[2]
+      .replace(/&amp;/g, '&').replace(/&lt;/g, '<')
+      .replace(/&gt;/g, '>').replace(/&quot;/g, '"').trim();
+    if (!text || isNaN(time)) continue;
+    if (mode !== 1 && mode !== 4 && mode !== 5) continue;
+    items.push({ time, mode: mode as 1|4|5, fontSize: parseInt(p[2],10), color: parseInt(p[3],10), text });
+  }
+  return items.sort((a, b) => a.time - b.time);
+}
+
+export function danmakuColorToCss(color: number): string {
+  return '#' + (color >>> 0 & 0xFFFFFF).toString(16).padStart(6, '0');
+}