[Linuxuser67]

Summary

• Require a random per-run Basic credential on the loopback SSRF-guard proxy; pass its credential-bearing URL only through child proxy environment variables, not logged argv.
• Avoid signalling a potentially recycled process-group ID after the direct child has been reaped.
• Bound yt-dlp impersonation-probe output and drain time, retaining child ownership across the process timeout.
• Add regression coverage for unauthenticated proxy requests, authenticated private-target rejection, and guarded argv validation.

Independent review

Verified the missing proxy authentication and both post-reap signalling paths in gallery_probe.rs and video_tools.rs. The changes preserve the private-address filtering and make process-group signals only while the probe child is still owned and unreaped.

Rust/GTK compilation and tests are delegated to CI; the local environment does not provide the repository's GTK 4.22 / libadwaita 1.9 development packages.