release 1.21.0

🎉🧨🎆 Happy Chinese & Luna New Year / 祝大家新年快乐 🥳🍷🍻

Add bilibili subscription support / 新增 Bilibili 订阅支持 #78
Add S3 storage support / 新增 S3 存储支持 #38
Added global download default configuration function / 新增全局下载默认配置功能 #93
Add YouTube Data API usage limits and statistics / 新增 YouTube Data API 使用限额与统计功能 #94
Add batch download functionality for historical episodes / 新增历史节目批量下载能力 #96
Upgrade keyword filtering from simple OR to OR + AND patterns / 关键字过滤从仅“或”升级为支持“或 + 与” #87
Simplify deployment configuration by moving storage policy and base URL config to web page and database storage / 将存储策略与 base url 配置迁移到网页和数据库存储，简化部署配置
Use yt-dlp --flat-playlist with YouTube Data API to reduce calls and improve sync performance / 结合 yt-dlp --flat-playlist 与 YouTube Data API 提升同步性能并减少 API 调用 #94
Add itunes:category and itunes:explicit tags in RSS and adjust chapter type / RSS 新增 itunes:category 与 itunes:explicit，并调整 chapter type #84
Optimize FeedHeader UI / 优化 FeedHeader UI
Add supported URL ID format hints / 新增受支持 URL ID 格式提示

Separate channel and playlist views to avoid source interference for same-channel episodes / 分离频道与播放列表视图，避免同频道节目时订阅源互相干扰
Optimize performance when syncing playlists with a large number of episodes, reduce memory usage, and avoid OOM on machines with limited memory / 优化大节目数量播放列表同步时的性能，减小内容占用，避免在小内存机器上 OOM #86

Add bilibili subscription support / 新增 Bilibili 订阅支持 #78
Add S3 storage support / 新增 S3 存储支持 #38
Added global download default configuration function / 新增全局下载默认配置功能 #93
Add YouTube Data API usage limits and statistics / 新增 YouTube Data API 使用限额与统计功能 #94
Add batch download functionality for historical episodes / 新增历史节目批量下载能力 #96
Upgrade keyword filtering from simple OR to OR + AND patterns / 关键字过滤从仅“或”升级为支持“或 + 与” #87
Simplify deployment configuration by moving storage policy and base URL config to web page and database storage / 将存储策略与 base url 配置迁移到网页和数据库存储，简化部署配置
Use yt-dlp --flat-playlist with YouTube Data API to reduce calls and improve sync performance / 结合 yt-dlp --flat-playlist 与 YouTube Data API 提升同步性能并减少 API 调用 #94
Add itunes:category and itunes:explicit tags in RSS and adjust chapter type / RSS 新增 itunes:category 与 itunes:explicit，并调整 chapter type #84
Optimize FeedHeader UI / 优化 FeedHeader UI
Add supported URL ID format hints / 新增受支持 URL ID 格式提示

Separate channel and playlist views to avoid source interference for same-channel episodes / 分离频道与播放列表视图，避免同频道节目时订阅源互相干扰
Optimize performance when syncing playlists with a large number of episodes, reduce memory usage, and avoid OOM on machines with limited memory / 优化大节目数量播放列表同步时的性能，减小内容占用，避免在小内存机器上 OOM #86