Give a song, a track or an item a sound FX of its own (#355)

A sound FX for one place in a song had to be a project asset, which
then stood in every picker. Now every pick of a sound FX in a song
can make one the song keeps for that place alone, on top of the
embedded assets of the first two parts.

- Create sound FX sits at the end of the Sound FX row of the song,
  a track and an item, and of the menu of a track's FX button. It
  makes "Sound FX 1", 2, … per song with the Input wired to the
  Output, picks it and opens it. That is one undo step.
- Embed a copy, while the place names a project FX, gives the place
  a copy under the same name.
- While the place names its own, the menu shows it with the mark and
  offers Edit sound FX and Make project asset.
- Picking anything else lets it go in the same undo step. For a
  track or an item `settleEmbedded` did that already. For the song's
  own row `AssetPropertyCommand` now settles the song after `fx`.
- The mark `•` moved to the core. `assetRefLabel` puts it in front of
  an embedded asset, so the inspector rows show it like the timeline.
- `FieldHandlers.moreChoices` lets a caller end a reference menu
  with entries of its own. `embeddedPatternName` is `embeddedName`
  with a base now.

Tests:
- Unit own-fx (new): 6 green, 6 counter-checks each red
- Unit embedded and 80 neighbouring files: 1434 green
- e2e 65 (melektaus-atx): ALL PASSED, 51 checks (2 new)
- Gate (melektaus-atx): CHECK EXIT 0, 270 files, 4178 tests

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

tests/core/embedded.test.ts

@@ -21,7 +21,7 @@ import {
   assetTitle,
   embeddedCopy,
   embeddedIn,
-  embeddedPatternName,
+  embeddedName,
   embeddedUsedBy,
   instrumentNear,
   isRowHiddenWhenEmbedded,
@@ -234,7 +234,7 @@ describe('a pattern made in a song (#355)', () => {
     const make = (props: Record<string, string | number> = {}) => {
       const made = new CreateAssetCommand(
         'pattern',
-        embeddedPatternName(f.project, songId),
+        embeddedName(f.project, songId, 'Pattern'),
         { ...songClockProps(s.song().props), bars: 1, ...props },
         songId,
       );