Adds _FrameGrabber which decodes in a background thread and keeps only the
newest frame; VideoSource drop_stale (STREAM only) returns the latest frame
so a slow consumer never builds a backlog. app enables it for streams.
REPLAY is unchanged. 82 tests pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Adds a mid-stream drop recovery test and a pipeline test proving a
disconnected frame yields no events and interrupts a pending suspect
(stream loss never alarms). Live preview and fall detection on the real
Hikvision stream were confirmed on Windows. 74 tests pass.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
ilaandClaude Opus 4.8