feat: resolve trial-only playback via trialDuration/effectiveDuration

VIP songs for non-VIP accounts return a ~30s trial fragment. The player used the full duration for isNearEnd, so the trial end didn't trigger auto-advance (~60s stall), and currentSong.duration stayed full, leaving the UI progress stuck.

- provider.ts: SongUrlResult {url, trialDuration?}; getSongUrl signature
- netease.ts: parseNeteaseTrial (freeTrialInfo start/end in seconds) + getSongUrl
- qq.ts: parseQqTrial (isTryout/tryEnd) + getSongUrl
- bilibili/youtube: getSongUrl returns {url}
- instance.ts: resolveAndPlay uses effectiveDuration = trialDuration ?? duration -> nearEnd at trial end -> native auto-advance; BotStatus.effectiveDuration
- VIP account: freeTrialInfo absent -> full duration -> full playback (no toggle)

Backward compatible (optional fields; getSongUrl has a single caller, updated).
Tests: parseTrial assertions (seconds/alias/ms-fallback). 14 pass.

src/music/bilibili.ts

@@ -3,6 +3,7 @@ import axios, { type AxiosInstance } from "axios";
 import type {
   MusicProvider,
   Song,
+  SongUrlResult,
   Playlist,
   LyricLine,
   SearchResult,
@@ -231,7 +232,7 @@ export class BiliBiliProvider implements MusicProvider {
     return this.cidCache.get(bvid) ?? null;
   }
 
-  async getSongUrl(songId: string, _quality?: string): Promise<string | null> {
+  async getSongUrl(songId: string, _quality?: string): Promise<SongUrlResult | null> {
     const cid = await this.getCid(songId);
     if (!cid) return null;
 
@@ -253,7 +254,8 @@ export class BiliBiliProvider implements MusicProvider {
         (b.bandwidth ?? 0) > (a.bandwidth ?? 0) ? b : a
       );
 
-      return best.baseUrl ?? best.base_url ?? null;
+      const biliUrl = best.baseUrl ?? best.base_url;
+      return biliUrl ? { url: biliUrl } : null;
     } catch {
       return null;
     }