Salo Dual Camera: Speedometer

Fixed speedometer behavior: it now appears reliably before recording and updates correctly in PiP modes.
Improved speedometer overlay sizing to prevent sudden size jumps.
Improved PiP stability and rendering for Rect / Circle / Square modes.
Fixed circle PiP export issues (cut/cropped edges) and reduced random position jumps.
Fixed split-screen (horizontal/vertical) camera scaling so front camera is no longer squeezed.
General recording and camera stability improvements.