Let a variable hold a list

A variable could only be a number, a text or a yes/no, so every set of values had
to be smuggled through a string - which is where Tetris got its unreadable
"03066326048763714" colours from. A list is now a value of its own, with an item
kind (number, text, yes/no, colour) that decides how the inspector reads the one
comma-separated line it is typed as, and eight nodes to work with: List, Fill,
Count, Item at, Set item, Sub list, Join lists, Index of.

Two traps came with it. An array is typeof 'object', so every place that told a
value from an entity had to learn the difference, or a list would have been
passed around as a game object. And a value was compared by identity in three
places - with lists that marks everything as an overridden property after each
reload, so those comparisons now compare contents.

There is no list of objects: a list is written to the project file and an object
is a live handle that no reload survives. A set of objects stays a list of names.

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

src/core/graph/Graph.ts

@@ -1,7 +1,7 @@
 import type { PropertyBag } from '../model/Properties';
 
 /** `exec` carries control flow, the others values; `any` accepts every value type. */
-export type PortType = 'exec' | 'number' | 'boolean' | 'string' | 'object' | 'any';
+export type PortType = 'exec' | 'number' | 'boolean' | 'string' | 'object' | 'list' | 'any';
 
 export interface PortRef {
   node: string;
@@ -31,7 +31,7 @@ export interface DeclaredPort {
   kind: DeclaredPortKind;
 }
 
-export const DECLARED_PORT_KINDS = ['number', 'boolean', 'text', 'object'] as const;
+export const DECLARED_PORT_KINDS = ['number', 'boolean', 'text', 'object', 'list'] as const;
 export type DeclaredPortKind = (typeof DECLARED_PORT_KINDS)[number];
 
 export function declaredPortType(kind: DeclaredPortKind): PortType {