v4.9.0

New features

• Source health engine: a 403, 401, 429, or Cloudflare/captcha challenge page from a proxy endpoint now blacklists it immediately instead of counting as a success; after 3 consecutive failures an endpoint is marked dead and never revived for the session (superseded by the backoff system in v4.10.0), and IsAvailable() for Qobuz/Amazon now returns false once every endpoint is dead so the orchestrator skips straight to Soulseek instead of timing out first. Each source in the fallback chain is also wrapped in its own panic recovery, so one source panicking no longer aborts the rest of the chain.
• Source Health panel (Settings > Status): a Check Sources button runs concurrent live probes, bounded to 8s per source, Qobuz/Amazon over real proxy requests and Soulseek as an instant local check to avoid ban risk, reporting online, degraded, or dead with latency and a reason.
• One-click sldl installer (Settings > Soulseek): downloads, extracts, and installs the pinned Soulseek client release for the current platform with a progress bar, and re-initializes the Soulseek source without a restart.

Internal

• First Go test suite for the download orchestration chain: endpoint blacklisting/revival, orchestrator panic isolation, and Soulseek output parsing.
• Core dependency bumped to v0.10.7.