Begin a new local stroke. Returns the new stroke's id. Use the id
with appendPoints and endStroke to extend / commit it.
aspectRatio is the source content aspect ratio at the moment
the stroke begins (reported by useVideoContentRect).
True when this caller is allowed to clear-all.
True when this caller is allowed to draw.
True when this caller is the room owner — drives whether the toolbar shows the lock toggle.
Remove every stroke. Gated by clearAllPermission.
Remove only this caller's strokes.
When true, drawing is locked to the room owner only. Synced
across all peers via the data-channel — when one owner toggles
the lock, every peer's canDraw updates accordingly.
Commit the stroke (final pointer-up).
Toggle the room-wide drawing lock. Only the room owner can call
this — non-owners see no-op (and the toolbar should hide the
toggle for them via canSetDrawingLock).
Live stroke set keyed by stroke id.
Append normalised points to an in-progress stroke.