Let a list hold structs, and read or write variables in bundles

A list item may now be a struct. The depth is bounded in the declaration
rather than by a comment: FieldKind (number|text|boolean|color) says what a
struct field holds, ListItemKind adds struct on top and says what a list
holds, so list -> struct -> primitive is the deepest storable shape and
sameValue stays finite. A struct item renders inline in the List tab, which
is why it needs no path in the slot address.

Four paths silently assumed a list item was a primitive: sameValue compared
items with ===, textOf would have printed [object Object], asListItem turned
a struct into text on Set item and Fill, and Index of used indexOf, which is
reference equality and could never have found a struct.

Tetris now runs on bundles. shapes is 112 {x, y} structs instead of 224 loose
numbers, piece and the candidate are structs, so Next move hands back a whole
candidate and each strand packs only the field it changes, since mergeStruct
leaves the rest standing. Declared behavior ports drop 49 -> 35, the master's
variables 18 -> 13, its graph 84/94 -> 69/76 nodes/edges.

Get variables and Set variables declare their ports from a list of variable
names, the way Pack and Expand already do, so one node can read or write
several at once. Renaming a variable rewires them, because there the port key
is the variable name.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>

src/editor/inspector/nodeSection.ts

@@ -1,6 +1,7 @@
 import { RemoveNodeCommand, SetNodeParamCommand } from '../../core/commands/graphCommands';
 import {
   callProblem,
+  declaresVariablePorts,
   type Graph,
   edgesInto,
   type GraphNode,
@@ -16,7 +17,7 @@ import type { PropertyDef } from '../../core/properties/PropertySchema';
 import { Button, Label } from '../../ui';
 import { createFieldRow, type FieldHandlers } from './fieldFactory';
 import { addGap, addNote, addTitle, type InspectorHost } from './host';
-import { buildPortSection } from './portSection';
+import { buildPortSection, buildVariablePortSection } from './portSection';
 import { listOpener, previewingHandlers } from './previewHandlers';
 
 /** Structure-defining facts of a node selection: ports, connected inputs, declared variables. */
@@ -51,7 +52,8 @@ export function buildNodeSection(host: InspectorHost, assetId: string, nodeId: s
   addNote(host, def.description);
   const problem = callProblem(node, behaviorLookup(host.state.project), assetId);
   if (problem) addNote(host, problem, 'warning');
-  if (def.declaresPorts) buildPortSection(host, assetId, node);
+  if (declaresVariablePorts(node.type)) buildVariablePortSection(host, assetId, node, asset.variables);
+  else if (def.declaresPorts) buildPortSection(host, assetId, node);
 
   if (def.params.length > 0) addTitle(host, 'SETTINGS');
   for (const param of def.params) {