Add flinger.SetConfig to update FPS/quality/name/audio/announce without
restarting the stream. Fields that require a restart (source, port,
stream-index) are preserved. The video loop reads the live config each
frame so changes apply immediately, and the GUI Quality/Frame-rate
dropdowns push changes to a running engine.
Verified live: fps 12->33 and JPEG size 210KB->1.3MB on quality change.
petere
95f47abadb