Refactoring: one file per node, consistent comments, shared helpers, split large modules

- Graph: nodes.ts split into nodes/<category>/<Type>.ts (62 files) with
  shared.ts factories and index.ts registry; NodeContext/values/NodeRegistry
  separated, writeTyped() replaces duplicated typed writes
- Comments: one style (JSDoc on non-obvious exports, // for decisions and
  traps), wrong/stale comments fixed or removed, ids.ts now real 10 base-36 chars
- Core: chainOf, shared worldPosition/editorPosition core, commands/require.ts,
  commands/naming.ts, util/list.ts, setBagValue/toPosition/propDef; dead code
  removed (isBehaviorAsset, SCENE_OBJECT_SCHEMA, CommandStack.subscribe,
  Input.axis, setMode, titleText, World.worldPosition, unused ctor params)
- Editor: Inspector split into inspector/ sections, App.ts into Editor.ts +
  debugHook.ts + shortcuts.ts, Viewport into items.ts + symbols.ts, shared
  "Add collider" action, unified type labels/swatches
- UI toolkit: Widget.trackHover/onPointerRelease, drawControlBox, math helpers,
  Popup.openBelow, Menu/Dialog/ColorPicker/ListRow in own files, named Theme sizes
- Tools: seed-demo/smoke-demo and demo-check project removed, tools/lib
  (harness, projects, builders), e2e.mjs as runner over tools/e2e/*.mjs sections
- Tests: tests/helpers.ts replaces copied fixtures and NodeContext doubles

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

src/core/graph/nodes/index.ts

@@ -0,0 +1,95 @@
+import { type NodeDef, registerNode } from '../NodeRegistry';
+import { Destroy } from './action/Destroy';
+import { Log } from './action/Log';
+import { Move } from './action/Move';
+import { RestartGame } from './action/RestartGame';
+import { SetEnabled } from './action/SetEnabled';
+import { SetPosition } from './action/SetPosition';
+import { SetProperty } from './action/SetProperty';
+import { SetText } from './action/SetText';
+import { Spawn } from './action/Spawn';
+import { StopGame } from './action/StopGame';
+import { Abs } from './data/Abs';
+import { Add } from './data/Add';
+import { And } from './data/And';
+import { AxisInput } from './data/AxisInput';
+import { BooleanLiteral } from './data/Boolean';
+import { Ceil } from './data/Ceil';
+import { Clamp } from './data/Clamp';
+import { Compare } from './data/Compare';
+import { Distance } from './data/Distance';
+import { Divide } from './data/Divide';
+import { Equals } from './data/Equals';
+import { Floor } from './data/Floor';
+import { GetPosition } from './data/GetPosition';
+import { GetProperty } from './data/GetProperty';
+import { IsAsset } from './data/IsAsset';
+import { IsEnabled } from './data/IsEnabled';
+import { IsHovered } from './data/IsHovered';
+import { IsTouching } from './data/IsTouching';
+import { Join } from './data/Join';
+import { KeyIsDown } from './data/KeyIsDown';
+import { Length } from './data/Length';
+import { Max } from './data/Max';
+import { Min } from './data/Min';
+import { Modulo } from './data/Modulo';
+import { MouseButton } from './data/MouseButton';
+import { MousePosition } from './data/MousePosition';
+import { Multiply } from './data/Multiply';
+import { NameOf } from './data/NameOf';
+import { Normalize } from './data/Normalize';
+import { Not } from './data/Not';
+import { NumberLiteral } from './data/Number';
+import { ObjectByName } from './data/ObjectByName';
+import { Or } from './data/Or';
+import { Owner } from './data/Owner';
+import { Parent } from './data/Parent';
+import { Random } from './data/Random';
+import { Round } from './data/Round';
+import { Self } from './data/Self';
+import { Sqrt } from './data/Sqrt';
+import { StringLiteral } from './data/String';
+import { Subtract } from './data/Subtract';
+import { Time } from './data/Time';
+import { ToText } from './data/ToText';
+import { OnClick } from './events/OnClick';
+import { OnCollisionEnter } from './events/OnCollisionEnter';
+import { OnCollisionExit } from './events/OnCollisionExit';
+import { OnCollisionStay } from './events/OnCollisionStay';
+import { OnKeyDown } from './events/OnKeyDown';
+import { OnKeyHeld } from './events/OnKeyHeld';
+import { OnKeyUp } from './events/OnKeyUp';
+import { OnStart } from './events/OnStart';
+import { OnTimer } from './events/OnTimer';
+import { OnUpdate } from './events/OnUpdate';
+import { Branch } from './flow/Branch';
+import { Sequence } from './flow/Sequence';
+import { GetVariable } from './variable/GetVariable';
+import { SetVariable } from './variable/SetVariable';
+
+/**
+ * The built-in node set, one definition per file. Importing this module registers them;
+ * the palette sorts by category and label, so the order here is documentation only.
+ */
+export const BUILT_IN_NODES: readonly NodeDef[] = [
+  // events
+  OnStart, OnUpdate, OnKeyDown, OnKeyUp, OnKeyHeld, OnTimer,
+  OnCollisionEnter, OnCollisionStay, OnCollisionExit, OnClick,
+  // flow
+  Branch, Sequence,
+  // variables
+  GetVariable, SetVariable,
+  // data: references and properties
+  Self, Owner, Parent, ObjectByName, NameOf, IsAsset, IsEnabled, GetProperty, GetPosition,
+  // data: literals and math
+  NumberLiteral, BooleanLiteral, StringLiteral,
+  Add, Subtract, Multiply, Divide, Min, Max, Abs, Sqrt, Clamp, Floor, Ceil, Round, Modulo, Random, Time,
+  // data: text and comparison
+  ToText, Join, Equals, Compare, And, Or, Not,
+  // data: vectors and input
+  Length, Distance, Normalize, AxisInput, KeyIsDown, MousePosition, MouseButton, IsHovered, IsTouching,
+  // actions
+  Move, SetPosition, SetProperty, SetEnabled, SetText, Spawn, Destroy, Log, StopGame, RestartGame,
+];
+
+for (const def of BUILT_IN_NODES) registerNode(def);