Describe the Parametric EQ's zoom, saved on its node (#376)

- Sounds: the wheel on free space zooms the curve's dB, the steps,
  the grid, handles on the edge, saved as `range` and no undo step.
- Sounds: the wheel turns the Q only over a handle now, and the node's
  curve is zoomed as the tab is.
- Development: 1922 editor checks.

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

Development.md

@@ -19,7 +19,7 @@ php tests/php/accounts.test.php                               # the API's accoun
 php tests/php/snapshots.test.php                              # the snapshot store (#231), the same way
 php tests/php/releases.test.php                               # the release store (#266), the same way
 php tests/php/files.test.php                                  # uploaded files in a folder per account (#344), the same way
-node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1921 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1922 editor checks, screenshots in /tmp/gm-e2e-*.png
 GM_STEPS=20 node tools/e2e.mjs                                # or 1-12, or 6,20 — a subset while working on one step
 ./e2e.sh start [GM_STEPS]                                     # the same run detached, see below
 ./e2e.sh status                                               # live progress, or the last run's result

Sounds.md

@@ -595,11 +595,18 @@ opens its editor, in a sound FX and in an instrument alike.
   loaded. *Play* is in the sound FX's tab, not in the EQ's:
   float one of the two (see *The tab row* in [Concepts](Concepts)) to have both in view.
 - **Delete** in the EQ's tab removes the picked band, never the node.
-- **The curve** takes the room of the tab and shows 20 Hz to 20 kHz in octaves and -24 to +24 dB.
+- **The curve** takes the room of the tab and shows 20 Hz to 20 kHz in octaves and, unless zoomed,
+  -24 to +24 dB.
   The thick line is all bands together, each band has a thin line in its own colour and a
   numbered handle.
+- **Zoom** (#376): the mouse wheel on free space zooms the dB the curve shows, always the same
+  either side of 0: ±3, ±6, ±12, ±24 or ±48 dB. Up zooms in. The lines across the curve follow,
+  every 1, 2, 3, 6 or 12 dB. A band whose gain is beyond the range keeps its handle on the edge,
+  where it can still be grabbed. The zoom is saved on the node (`range`), so it is there again
+  after loading, and it is no undo step: Ctrl+Z undoes edits, not a look at the curve. The
+  spectrum keeps its own scale.
 - **In the node** (#375) the curve of all bands is drawn in small below its rows, on the same
-  axes: the 0 dB line, the area up or down to the curve, and the curve. Without a band the box
+  axes, zoomed as the tab is: the 0 dB line, the area up or down to the curve, and the curve. Without a band the box
   stays, flat, so the node does not grow at the first one. It follows every change, a drag in the
   tab as well. A double-click on it opens the tab like anywhere on the node.
 - **The spectrum** (#374): while the EQ's tab is seen, in the tab row or in a window, it draws
@@ -611,23 +618,23 @@ opens its editor, in a sound FX and in an instrument alike.
   analyser, so it falls away softly once the sound has gone. While the tab is not seen, no
   analyser is fed.
 - **With the mouse:** a double-click on free space adds a peak there. Dragging a handle moves the
-  band's frequency and, for a peak or a shelf, its gain. The mouse wheel over a handle, or anywhere
-  while a band is picked, makes it a sixth of an octave narrower or wider. A right-click on a
-  handle removes the band.
+  band's frequency and, for a peak or a shelf, its gain. The mouse wheel over a handle makes the
+  band a sixth of an octave narrower or wider, anywhere else it zooms (see above). A right-click on
+  a handle removes the band.
 - **Below the curve** are the numbers of the picked band: *Type*, `Hz`, `dB`, `Q` and *Slope*.
   A row the type does nothing with is greyed out.
 - **Types:** *Peaking*, *Low shelf*, *High shelf*, *Low cut* (a high-pass), *High cut* (a
   low-pass), *Band-pass* and *Notch*. *Slope* (12, 24 or 48 dB/oct) is there for the cuts, the
   band-pass and the notch, as on the [Filter](#filter). A shelf has no Q.
 - **Ranges:** frequency 20 to 20000 Hz, gain -24 to +24 dB, Q 0.1 to 30.
-- **One undo step** for each drag, each scrub of a field, each wheel notch, each added or removed
-  band.
+- **One undo step** for each drag, each scrub of a field, each wheel notch on a handle, each added
+  or removed band.
 - **What is heard:** each band is one `BiquadFilterNode` per voice, or 2 or 4 for a steeper
   slope. A peak or a shelf at 0 dB is left out. The curve is worked out with the formulas Web Audio
   uses, at 48 kHz. In front of the bands and behind them every voice and every bus has a tap, a
   gain of 1 that does nothing to the sound. Only while the tab is seen do the taps of that node
   feed its analysers. A bypassed EQ keeps its taps.
-- The bands are saved on the node as a list (`bands`). They have no input, so a parameter of the
+- The bands are saved on the node as a list (`bands`), the zoom as a number (`range`). They have no input, so a parameter of the
   Input or an Envelope cannot move them. Bypass and `wet` work as on every effect.
 
 ### Compressor and Limiter