Migrate the server-side live downloading to the new biliup::downloader::live API and simplify the actor model. Key changes:
- Introduce a new server/core/live module that builds LiveRequest/LiveOptions/LiveCredentials, maps runtimes, and creates danmaku clients.
- Replace legacy plugin/DownloadBase actor flow with LivePlugin-based workflows and a start_download_workflow entrypoint; monitor now acquires a Semaphore permit before starting a download to enforce concurrency.
- Remove the old plugin module and per-platform plugin plumbing; many platform implementations were moved/renamed under crates/biliup/src/downloader/live.
- Adjust DownloadManager, Monitor, and common download/upload code to use LivePlugin, LiveStream and related types; pass uploader channel and download slot semaphore into Monitor.
- Add download_stream helper to support direct FLV/HLS downloads via StatelessClient, and extend Streamlink downloader to support Niconico credentials/options.
- Update usage of context/streamer info and danmaku initialization to the new LiveStream-based model.
- Bump workspace version to 1.2.0 (Cargo.toml) and related package versions.
This refactor centralizes live logic on the shared biliup downloader live API, simplifies concurrency control, and removes the previous actor-based plugin indirection.
Refactored the DownloadTask::execute method to return DownloadStatus and adjusted its visibility. Enhanced DActor message handling to update stream info after download execution. Updated README and introduction guide with improved instructions for background running and systemd service configuration.
ForgQi