For wtv cucked reason all the viewbox/scene coordinate calcs do **not**
include a left axis in the geo (likely because it's a hacked in widget
+ layout thing managed by `PlotItem`). Detect if there's a left axis and
if so use it in the label placement scene coords calc. ToDo: probably
make this a non-move calc and only recompute any time the axis changes.
Other:
- rate limit mouse events down to the 60 (ish) Hz for now
- change one last lingering `'ohlc'` array lookup
- fix `.mouseMoved()` "event" type annot
09fc901b0d