Open a Compressor as a device in a window of one size (#379)

The tab from #378 shows a Compressor as an editor. The user wanted it
to look like a device as well, after a brushed aluminium plug-in, with
a meter of the gain reduction instead of the pictures. The tab stays
and is switched to per node.

- Hardware look is a switch under Settings, on by default for new and
  existing Compressors. Only the editor reads it.
- The panel is 820x280 px and opens straight in a window of that size.
  The window has no sizing corner and no Dock. A pane says so through
  `fixedSize`, and `keptSize` keeps the window's middle when it
  changes to that size.
- A Compressor in this look never sits in the tab row. Opening one
  floats it, and switching the look on moves its tab into the window.
- The panel has chrome knobs (threshold and makeup large), a meter
  with a needle that moves like a VU's, an LCD with the name and the
  reading, a lever with a lamp for auto-gain, and LEDs for the level
  going out. Everything is drawn in code.
- The Knob takes a size and a chrome look, and leaves out its caption
  when it has no name, so the panel engraves its own.
- `autoGainOn` is now `switchOn`, because the new switch reads the
  same way.
- Where parts sit, the meter's scale, the needle's speed, the LEDs and
  the plate's grain are in `hardwareView.ts`, apart from the drawing.

Decided myself:
- The meter's scale runs by the square root, so the first dB is about
  as wide as the last nine. It is red from 10 dB on.
- The LEDs light one every 3 dB from -39 to 0 dB and fall by 20 dB a
  second.
- Switching the look changes the graph's fingerprint, like any other
  setting of a node. The sound FX is built again once.

Findings, fixed on the way:
- Pixi's `arc` goes on from the last point of the path. The meter's
  scale had a line from the corner of the face until each arc got a
  `moveTo` to its own start.
- A text put into a Graphics makes Pixi warn that only Containers take
  children. The LCD is a Container now.
- The first browser check read the needle at one moment and missed the
  short sound. The panel keeps the most its needle and LEDs showed.

Tests:
- Unit: hardware-view (10 new), documents (1 new)
- e2e 34 (melektaus-atx): ALL PASSED, 122 checks (4 new). Played,
  the needle reached 20.9 dB and 5 LEDs lit.
- Gate (melektaus-atx): CHECK EXIT 0, 283 files, 4355 tests (11 new)
- Counter-checks: a window that keeps its corner instead of its
  middle, and a linear meter scale, each turn exactly their test red.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/editor/floating.ts

@@ -43,6 +43,17 @@ export function onScreen(box: WindowBox, screenW: number, screenH: number, least
   return { x: Math.round(x), y: Math.round(y), w: Math.round(w), h: Math.round(h) };
 }
 
+/** `box` at `size`, around the same middle: a window of one size (#379) opened in a box of another. */
+export function keptSize(box: WindowBox, size: { w: number; h: number }): WindowBox {
+  if (box.w === size.w && box.h === size.h) return box;
+  return {
+    x: Math.round(box.x + (box.w - size.w) / 2),
+    y: Math.round(box.y + (box.h - size.h) / 2),
+    w: size.w,
+    h: size.h,
+  };
+}
+
 /** `box` with its lower right corner pulled by `dx`, `dy`: at least the minimum, at most to the screen's edge. */
 export function sized(
   box: WindowBox,