Refactoring round 10: split SoundLibrary, fold sound duplicates (#85)

Refactoring round 10 covers everything since round 9 (808e1ee): 110
commits with about 47 000 new lines, nearly all of them sound, sound
FX, instruments, patterns and songs. Behaviour is unchanged.

Duplicate code (jscpd over src, 50 tokens, TypeScript only, measured
on 808e1ee and here alike: 47 clones / 426 lines before, 33 / 245
after; round 9 itself ended at 22 / 160 by this count):

- PreviewParams (new, editor/soundfx) is the header's parameter bar
  of the Sound FX and the Instrument tab: values, defaults, fields
  and the voices a moved field reaches. Both tabs had it line for
  line.
- fxWorklet: an Effect base runs the bit crusher, phaser, flanger,
  limiter, LFO and bus shifter, a Source base the pitch player and
  the Chip. Start is the one wait for a voice's first sample, which
  four processors wrote out each.
- nodes/shared has checkPort, detachedPort, fxParamsPort and
  letRingPort. The Play and Stop nodes of sounds, notes, patterns and
  songs spelled each port out, up to five times.
- parameterValues builds both Sound FX parameters and Instrument
  parameters, which differed in name and text only.
- SetLoopCommand sets the ruler loop of a pattern or a song. It
  replaces SetPatternLoopCommand and SetSongLoopCommand.
- addLink in music/routing is the one rule for a link that both the
  song routing and the Master routing keep.
- eqCurves works out each band and their sum for the EQ tab, which
  did that in its drawing code. It replaces eqCurveDb, which only a
  test called.
- Smaller ones: the eight neighbour directions of a tile cell, and
  drawFloatingBox for the shadowed box of Popup and FloatWindow.
- Left on purpose: Play pattern and Play song stay two parallel node
  definitions, and the smaller clones under ten lines stay.

Architecture:

- SoundLibrary.ts goes from 2897 to 2188 lines. What a stage of a
  sound FX becomes as Web Audio nodes, and how the knobs of a playing
  voice move, is now viewport/fxNodes.ts. None of it keeps state of
  the library.

Dead code (TS language service, references per export and member):

- soundRefIds, LFO_SHAPE_INDEX, TREMOLO_ROWS, VIBRATO_ROWS and
  REVERB_ROWS had no reader. The four routing node defs are
  registered without an unused exported name.
- soundFileOf and portTypeOf were called by tests only. The tests
  now ask findSound and portOf, which the editor uses. DRY moves
  from src into the one test that uses it.
- 51 values used only in their own file lose their `export`. Types
  and the node catalogues stay exported.
- Kept on purpose: neighboursOf is the cell by cell reading the
  indexed neighboursIn is checked against, and PitchShifter.latency
  is the test's one view of how late the shifter is.

Comments and docs:

- Seven comments told history ("no longer", "any more", "as
  before", "of before #354"). Nine comment blocks ran far past the
  line width. Proof that this changed no code: the bundle was md5
  identical, and the touched tests and e2e modules were identical
  after esbuild.
- README: sound FX, instrument, pattern, song and bus in the asset
  list, the pages Instruments, Patterns and Songs, 1919 checks.
- Wiki: see its own commit.

Tests:

  Gate (melektaus-atx)    274 files, 4236 tests, CHECK EXIT 0
  e2e 34, 64, 65          ALL PASSED, 180 checks
  Unit, touched areas     16 files, 804 tests

No check was added, the e2e sum stays at 1919. Counter-checks, each
put back by copy and compared with cmp:

- addLink without the loop rule: 2 tests fail, one per routing.
- eqCurves with the sum of the last band only: 1 test fails.
- Start in the worklet never waiting: e2e 34 fails in exactly the
  four checks that hang on a voice's first sample (Flanger, Tremolo,
  Chip, a pitched note planned ahead).

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

tools/e2e/65-song.mjs

@@ -3,15 +3,15 @@ import { LANES, pickAssetType, scaffoldBehavior } from './lib/scaffold.mjs';
 
 /**
  * Songs and their tracks (#334). "+ → Song" opens the tab on one empty track, a head's menu adds
- * three more. A pattern and a
- * sound dragged in from the Assets panel land as items where the preview showed them; an item's
- * right end lengthens it, its body moves it across tracks, its left end cuts it back or pulls it
- * out earlier, an end snaps to the end of a round, Ctrl+V lands under the pointer, Ctrl+D puts a
- * copy behind it, Ctrl+E splits it where playing starts, Delete or its menu takes it away. A click
- * on nothing picks the song, an end under the pointer lights up, a long item marks its rounds, the
- * wheel zooms tracks or time, the strip above the ruler sets the loop. A head mutes, solos and sets
- * the volume of its track, a double-click sets a slider back to 0, its menu adds one. Space plays the song through the scheduler:
- * the pattern round and round at the song's tempo, the sound as a clip, each track on its own bus.
+ * three more. A pattern and a sound dragged in from the Assets panel land as items where the
+ * preview showed them; an item's right end lengthens it, its body moves it across tracks, its left
+ * end cuts it back or pulls it out earlier, an end snaps to the end of a round, Ctrl+V lands under
+ * the pointer, Ctrl+D puts a copy behind it, Ctrl+E splits it where playing starts, Delete or its
+ * menu takes it away. A click on nothing picks the song, an end under the pointer lights up, a long
+ * item marks its rounds, the wheel zooms tracks or time, the strip above the ruler sets the loop. A
+ * head mutes, solos and sets the volume of its track, a double-click sets a slider back to 0, its
+ * menu adds one. Space plays the song through the scheduler: the pattern round and round at the
+ * song's tempo, the sound as a clip, each track on its own bus.
  * A pattern started meanwhile takes over, and a double-click opens a pattern item in its tab. Record
  * takes chromium's test tone onto a track of its own (#342), Esc throws a take away. A right-click
  * on an empty spot of a track makes a pattern the song keeps to itself (#355).
@@ -355,7 +355,7 @@ export async function song(t) {
   );
 
   // 65f-ii. A click on nothing picks the song; a sound item turns up to +12 dB in the inspector, which
-  //         has no delete button any more. An end of an item under the pointer shows it can be dragged,
+  //         has no delete button. An end of an item under the pointer shows it can be dragged,
   //         and an item longer than what it plays marks where it starts over.
   p = await json('__gm.song.laneAt(300, 3)');
   await click(p.x, p.y);