feat: add BiliBili audio source integration

Implement BiliBiliProvider for video-as-audio playback using direct
BiliBili API calls (search, video info, DASH audio URL extraction).
Add QR code login support and cookie persistence. Update FFmpeg to
send Referer header for BiliBili CDN URLs. Extend platform union type
to "netease" | "qq" | "bilibili" across all interfaces. Add -b flag
for chat commands and B站 badge in web UI.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/index.ts

@@ -6,6 +6,7 @@ import { createLogger } from "./logger.js";
 import { createApiServerManager } from "./music/api-server.js";
 import { NeteaseProvider } from "./music/netease.js";
 import { QQMusicProvider } from "./music/qq.js";
+import { BiliBiliProvider } from "./music/bilibili.js";
 import { createCookieStore } from "./music/auth.js";
 import { BotManager } from "./bot/manager.js";
 import { createWebServer } from "./web/server.js";
@@ -34,16 +35,20 @@ async function main() {
 
   const neteaseProvider = new NeteaseProvider(apiServer.getNeteaseBaseUrl());
   const qqProvider = new QQMusicProvider(apiServer.getQQMusicBaseUrl());
+  const bilibiliProvider = new BiliBiliProvider();
 
   const cookieStore = createCookieStore(COOKIE_DIR);
   const neteaseCookie = cookieStore.load("netease");
   if (neteaseCookie) neteaseProvider.setCookie(neteaseCookie);
   const qqCookie = cookieStore.load("qq");
   if (qqCookie) qqProvider.setCookie(qqCookie);
+  const bilibiliCookie = cookieStore.load("bilibili");
+  if (bilibiliCookie) bilibiliProvider.setCookie(bilibiliCookie);
 
   const botManager = new BotManager(
     neteaseProvider,
     qqProvider,
+    bilibiliProvider,
     db,
     config,
     logger
@@ -55,6 +60,7 @@ async function main() {
     botManager,
     neteaseProvider,
     qqProvider,
+    bilibiliProvider,
     database: db,
     config,
     logger,