Describe the Sample device and its waveform (#400)

- Instruments: what the gold device shows and how its parts are set.
- Architecture: SamplePanel, SampleFace and sampleView.
- Development: 1976 editor checks.

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

Architecture.md

@@ -453,6 +453,10 @@ src/editor/soundfx/    SoundFxEditor (#311: the graph, a sound to try it on, Pla
                        CrusherPanel + CrusherFace + crusherView (#399: the Bitcrusher as a device,
                        a sine sent through the node's own `Crusher` and drawn in cells of its steps
                        and holds, and the bits it keeps, worked out apart from the drawing),
+                       SamplePanel + SampleFace + sampleView (#400: the Sample as a device, the
+                       waveform of its sound or clip from the library's peaks, cut into what is
+                       played once, looped, played after the note and never heard, worked out
+                       apart from the drawing),
                        nodeParamDrag (a knob's drag as one undo step, for the tab and the
                        node, several settings at once since #389), nodeTabs (which nodes open a tab of
                        their own)

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                 # 1975 editor checks, screenshots in /tmp/gm-e2e-*.png
+node tools/seed-e2e.mjs && node tools/e2e.mjs                 # 1976 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

Instruments.md

@@ -44,6 +44,30 @@ stopped any more: a drone in a game is a *Loop* played by `Play note` with `dura
 it until a `Stop sound`. A Sample saved with the former **Mode** and **Loop** is loaded as one of
 these: *Gate* or *One-shot* without Loop stays what it was, either with Loop becomes *Loop*.
 
+**The Sample is a device** (#400), a compact 480x280 graph units, a plate in polished gold.
+`trigger` is on the left, `out` on the right, and everything is set right in the graph:
+
+- the **sound** is picked from the button beside the name, sounds and their [clips](Sounds#clips)
+  alike, as in the inspector;
+- a screen, **Waveform**, draws the sound or clip across its whole length, mirrored about the
+  middle, as loud as its volume plays it. Seconds run along the bottom, the length (and the volume,
+  where it is not 1) stands on the bezel. What becomes of each part has a colour of its own: gold
+  is played once, the **loop** is pale gold on a lit band between two lines, what *Loop, then
+  release* plays once the note is let go is amber (*After the note*), and what a *Loop* never gets
+  to is dark. Under the glass it says how it plays (`LOOPS 500 ms TO 900 ms WHILE HELD`) and at
+  what pitch (`AS IT IS AT C4`, or `AS IT IS ON EVERY NOTE` without *Follow note*). The loop is
+  drawn as both ways of playing hold it: an end of 0 or past the sound is the end of the sound, a
+  start not before the end loops all of it. Without a sound the screen says why: *No sound
+  picked*, *That sound is gone*, *The sound has no file*, *Loading* or *Cannot load*;
+- a button for each **Play**, *Gate*, *One-shot*, *Loop* and *Loop+rel*, two by two;
+- **Root** as a chrome knob that reads as a note (C4), and **Follow note** as a lever beside it
+  (*Follow*). A drag is one undo step, a double-click goes back to C4;
+- **Start** above **End** of the loop as fields in seconds, typed in or scrubbed sideways.
+
+Settings that do nothing as things stand are grey, as in the rows they replace: the root without
+*Follow note*, the loop's ends without a loop. Nothing on it moves by itself. A new instrument
+places its Output past the device.
+
 **Triggers.** The outputs of a Notes node that say "this note" are of their own kind, a
 **trigger**, drawn in lime. A trigger goes only into the `trigger` input of a source — nothing of a
 behavior can get in, and it fits nothing else. A `trigger` input takes any number of edges, and