Build a recording stability and pause/resume validation matrix

[rancy777]

Goal

Create and execute a repeatable validation matrix for the existing screen-recording path.

Cover

• MP4 playback and duration
• Pause/resume A/V continuity
• Repeated recordings and temporary-file cleanup
• Long-run memory, frame drops, and stability
• Closing windows or the app during recording
• Microphone and system-audio combinations where supported

A small automated smoke-test or diagnostic script is welcome, but a clearly documented manual matrix is a useful first contribution.