fix(video): ship FFmpeg DLLs as loose files, not inside single-file exe

[keyldev]

• ExcludeFromSingleFile on native Content: bundled DLLs extracted to a temp subpath the loader never probes -> every av_* call threw NotSupportedException
• FfmpegRuntime: classify NotSupportedException as native-load failure and replay the failure on later init calls (no endless cryptic reconnects)
• ONVIF: tolerate truncated GetSystemDateAndTime reply, assume zero time shift

Summary

• ExcludeFromSingleFile on native Content: bundled DLLs extracted to a temp subpath the loader never probes -> every av_* call threw NotSupportedException
• FfmpegRuntime: classify NotSupportedException as native-load failure and replay the failure on later init calls (no endless cryptic reconnects)
• ONVIF: tolerate truncated GetSystemDateAndTime reply, assume zero time shift

Related

Type

• Bug fix
• Feature
• Refactor / cleanup
• Docs / CI
• Other:

Checklist

• Builds with 0 warnings (TreatWarningsAsErrors=true).
• Tests pass (dotnet test); new Core logic has unit tests.
• No layering violation — App references Core only (Infrastructure / Video / Devices wired via DI in a head).
• Scope stays within one phase (didn't pull work from a later phase's "Не входит").
• README / docs updated if public commands, options, or setup changed.

Platforms tested

• Windows
• Linux
• macOS
• Android
• iOS
• CI build only

Screenshots / notes