Show lists in the inspector and variables in their own tab (#252)

The List tab could show one list at a time and was the only place to
see its items. A list now shows its items right where it lives, and a
new Variables tab shows all variables of an asset or placed object.

- InlineList draws the items of a list under its row in the inspector,
  in struct fields and in the Variables tab. A list inside a list or a
  struct field is drawn the same way, one step indented.
- The index column is the indent. Items sit under their list without an
  own margin, and the index column is 16 px wide instead of 28 px.
- Above 20 items (INLINE_LIMIT) the rest collapses into "... N more -
  open in tab". During a run the rows show the values from the game.
- ListHead puts "N items" and "+ Item" in one row. "N items" opens the
  list in a tab. A separate Open button squeezed the counter to zero
  width in the narrow inspector column.
- VariablesEditor shows every variable of a behavior asset, a variables
  asset or a placed behavior. On an asset it edits the declarations. On
  a placed object an edit only overrides that object, with the usual
  reset and push buttons.
- Opening a list inside a tab adds a new tab and keeps the open one.
  valuesKey gives each list its own document, so a list that is already
  open is shown instead of opened twice.
- Titles read "Pickup · Variables" or "Listy · nums · [3]". The tab
  closes when its asset or object is deleted.
- Lists on node inputs stay inline only, a node owns no variables.
- The List tab, ListEditor and the __gm.list hook are gone.

Tests:
- ./check.sh: 181 files, 2645 tests, CHECK EXIT 0
- GM_STEPS=1,21,22,32: ALL PASSED, 123 checks
- e2e 21 is rewritten for inline lists and the new tab, 22 and 32 are
  adapted. Sum in README: 1486 (+6 in 21, -1 in 22), counted by hand.
- Counter-probes fail as expected: sub-lists not told apart (1 unit
  test), sub-list replacing the open tab, all items drawn inline (60
  rows instead of 20), no live values (0 rows at 24 items in a run).

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

tools/e2e/22-struct.mjs

@@ -120,10 +120,10 @@ export async function structVariable(t) {
     JSON.stringify(await piece()),
   );
 
-  // 22f. A field may itself be a list. Its row is the same "n items" button a list property has,
-  //    and it opens the List tab one level down – on the field, not on the whole bundle.
+  // 22f. A field may itself be a list. Its items are drawn inline under it (#252), and its
+  //    title names the field inside the bundle – not the whole bundle.
   await clickText('+ Field');
-  // "List" is also the tab bar's own label, so the menu entry is reached as the last drawn one.
+  // "List" is also a word elsewhere on screen, so the menu entry is reached as the last drawn one.
   const listOption = await json(`__gm.locate('List', true)`);
   await click(listOption.x, listOption.y);
   check(
@@ -131,28 +131,32 @@ export async function structVariable(t) {
     Array.isArray((await piece()).field1),
     JSON.stringify(await piece()),
   );
-  const itemsButton = await find('0 items');
-  check('and that field reads as an item count', itemsButton !== null);
-
-  await click(itemsButton.x, itemsButton.y);
-  check('clicking it opens the List tab', (await json('__gm.tab()')) === 'list');
-  const info = await json('__gm.list.info()');
-  check('whose title names the field inside the bundle', info.title.endsWith('· field1'), info.title);
+  check('and that field reads as an item count', (await find('0 items')) !== null);
+  const fieldList = async () =>
+    (await json(`__gm.values.lists('inspector')`)).find((l) => l.title.endsWith('· field1')) ?? null;
+  const drawn = await fieldList();
+  check(
+    'whose items are drawn inline, titled by the field inside the bundle',
+    drawn !== null,
+    JSON.stringify(drawn),
+  );
 
   // Nothing bounds the depth any more (#239): a list in a struct field offers what any list does.
-  await clickText('+ Item');
+  const head = await json(`__gm.values.headAt('inspector', ${JSON.stringify(drawn?.title ?? '')})`);
+  await click(head.add.x, head.add.y);
   check(
     'the menu of a list in a struct field offers every kind, the struct included',
     (await find('Number')) !== null &&
       (await find('Struct')) !== null &&
-      (await json('__gm.list.info()')).offers.includes('list'),
-    JSON.stringify((await json('__gm.list.info()')).offers),
+      (await fieldList()).offers.includes('list'),
+    JSON.stringify((await fieldList()).offers),
   );
   await pickKind('Number');
   await sleep(250);
   check(
     'and an item added there leaves the neighbouring fields alone',
-    JSON.stringify(await piece()) === '{"column":30,"tag":"tee","field1":[0]}',
+    JSON.stringify(await piece()) === '{"column":30,"tag":"tee","field1":[0]}' &&
+      (await fieldList()).rows === 1,
     JSON.stringify(await piece()),
   );
   await shot('03-list-field');
@@ -164,8 +168,6 @@ export async function structVariable(t) {
     JSON.stringify(await piece()),
   );
 
-  await mutate('__gm.state.openList(null)');
-
   // 22f-ii. A field may be a struct again (#239): a head row with a `+ Field` of its own, and its
   //    fields one indent step further in. Both menus with real clicks.
   const declaredLast = () =>