cap the scale at 2x

The quarter steps did not actually shrink it. In a panel around 1500x950
device pixels the fit is 2.56, and floor(2.56 x 4) / 4 is still 2.5 — the finer
steps changed where the next size would land, not this one.

So a ceiling instead of another nudge: 2x, whatever room the panel has. That is
a taste decision rather than a limit of the method — past 2x this stops reading
as a window on a desktop — and the panel header has a zoom control, so it is a
default, not a verdict. Raise MAX_SCALE and the quarter steps take over again.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Officer-Session: de3ed4e6-f88a-429c-94e6-a760336ba83b

README.md

@@ -96,6 +96,10 @@ exactly 36 screen pixels, as even as at 2x, and only sub-cell pixels alternate.
 than halves because coarse steps overshoot — with halves this jumped 2x to 2.5x, too small to too large
 with nothing in between.
 
+The scale is then CAPPED at 2x. Fitting the panel is not the same as looking right, and past 2x this stops
+reading as a window on a desktop. That is a default, not a verdict — the panel header has a zoom control,
+and `MAX_SCALE` is one constant.
+
 Two things the scale has to know about that are easy to miss. `devicePixelRatio` is not the whole story:
 the panel header has its own CSS `zoom`, so the effective ratio is `devicePixelRatio × zoom`, read as
 `getBoundingClientRect().width / offsetWidth`. And the stage is fitted into the box MINUS a margin, because