Consolidate duplicated editor code, trim comments, refresh README

Split GraphCanvas (1076 -> 831 lines) into EdgeLayer and graphMenus;
the port and marker menus were the same list and are now one function.
Value specs of the inspector and the list tab share valueSpecs.ts, and
the remaining copies (compound commands, type glyphs, typed asset
lookup, name rule, play/editor world setup, marquee) are merged.

Four copies had already drifted apart; merging them fixes:
- "Disconnect N links" in the port menu is one undo step, not N
- "+ Add collider" is hidden on a placed container instance, as in
  the hierarchy menu, instead of always failing
- a bool property coerced from the text "false" becomes false
- a port command on an unknown node type reports instead of crashing

Comment-only edits leave the bundle byte-identical. README corrected in
35 places (step limit, jump-run clock, suite duration, 409 body, ...).

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

src/core/commands/variableCommands.ts

@@ -12,7 +12,8 @@ import type { Project } from '../model/Project';
 import {
   coerceValue,
   emptyFieldValue,
-  isCommonProp,
+  isValidFieldName,
+  isValidVariableName,
   type ListItemKind,
   type PrimitiveFieldDef,
   primitiveFieldsOf,
@@ -146,16 +147,6 @@ export class RenameVariableCommand implements Command {
 const INVALID_NAME = 'Variable names must start with a letter and contain only letters, digits or _';
 const INVALID_FIELD = 'Field names must start with a letter and contain only letters, digits or _';
 
-/** Identifier-like, and not a common property key – a variable "enabled" would shadow the switch. */
-export function isValidVariableName(name: string): boolean {
-  return isValidFieldName(name) && !isCommonProp(name);
-}
-
-/** A field lives inside its struct, so the reserved property keys do not apply to it. */
-export function isValidFieldName(name: string): boolean {
-  return /^[A-Za-z_][A-Za-z0-9_]*$/.test(name);
-}
-
 /** Where declared fields live: on a struct variable, or on the struct items of a list variable. */
 interface FieldOwner {
   /** True for a list of structs, where a field may not itself be a list (`ListFieldDef`). */
@@ -164,8 +155,12 @@ interface FieldOwner {
   setFields(next: readonly StructFieldDef[]): void;
 }
 
+function variableOf(project: Project, assetId: string, key: string): PropertyDef | undefined {
+  return requireBehavior(project, assetId).variables.find((v) => v.key === key);
+}
+
 function requireFieldOwner(project: Project, assetId: string, key: string): FieldOwner {
-  const def = requireBehavior(project, assetId).variables.find((v) => v.key === key);
+  const def = variableOf(project, assetId, key);
   if (def?.kind === 'struct')
     return {
       inList: false,
@@ -182,10 +177,8 @@ function requireFieldOwner(project: Project, assetId: string, key: string): Fiel
 }
 
 /**
- * Every value of one variable that carries a struct: the declared default, the behavior's own, and
- * each instance override – and for a list of structs, every item of each of those. A field is added
- * to or taken from all of them at once, so no value keeps a shape its declaration no longer
- * promises. The `id` is what pairs a site up again when the change is undone.
+ * One struct-carrying value of a variable (default, own, override, or list item); a field change hits
+ * all of them at once so none keeps a stale shape. `id` pairs a site up again on undo.
  */
 interface StructSite {
   id: string;
@@ -194,7 +187,7 @@ interface StructSite {
 }
 
 function structSites(project: Project, assetId: string, key: string): StructSite[] {
-  const def = requireBehavior(project, assetId).variables.find((v) => v.key === key);
+  const def = variableOf(project, assetId, key);
   const holders = valueHolders(project, assetId, key).filter(
     // An override the object does not have stays absent: writing one here would invent a deviation.
     (h) => !h.optional || (def?.kind === 'list' ? isList(h.read()) : isStruct(h.read())),
@@ -440,7 +433,7 @@ function requireListDef(
   assetId: string,
   key: string,
 ): Extract<PropertyDef, { kind: 'list' }> {
-  const def = requireBehavior(project, assetId).variables.find((v) => v.key === key);
+  const def = variableOf(project, assetId, key);
   if (def?.kind !== 'list') throw new CommandError(`Variable "${key}" is not a list`);
   return def;
 }