Add ESLint and Prettier, and close the node test gaps

Tooling:
- Prettier as the single formatting authority (110 columns, single quotes,
  measured against the existing style); Markdown excluded because table-cell
  padding turns the README glossary into 1000-character lines.
- Type-aware ESLint ending in eslint-config-prettier, so a rule always means
  "this is a bug", never "this looks different".
- .editorconfig and an `npm run check` that runs typecheck, lint, format and
  tests in one go.

Findings fixed on the first run: three more duplicate imports, four
String(unknown) calls (parameter types narrowed instead of casts), two dead
initialisers, two redundant casts, a console.log for a real error. Two
warnings were false here and are disabled with a reason in place.

Tests 132 -> 269:
- node-catalog.test.ts covers every node with a run(), with a guard that fails
  when a new node has no row.
- behavior-events.test.ts covers the ten event nodes through a running World,
  checking timing rather than existence.
- Input's state machine (press/release/releaseAll) is reachable without DOM
  events now; the DOM handlers are thin adapters.

Compare fell back to == without a configured operator although the schema
default is <; aligned.

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

src/core/graph/nodes/shared.ts

@@ -16,17 +16,34 @@ export const any = (key: string, label = key): PortDef => ({ key, label, type: '
 export const withDefault = (port: PortDef, value: PropertyValue): PortDef => ({ ...port, default: value });
 
 /** Outputs of the three collision events: the other body, its collider and the own collider. */
-export const collisionOutputs = (): PortDef[] => [exec(), obj('other'), obj('otherCollider', 'other collider'), obj('collider')];
+export const collisionOutputs = (): PortDef[] => [
+  exec(),
+  obj('other'),
+  obj('otherCollider', 'other collider'),
+  obj('collider'),
+];
 
 // --- params ----------------------------------------------------------------------------------
 
 export const keyParam: PropertyDef = { key: 'key', label: 'Key', kind: 'key', default: 'ArrowRight' };
 
 /** Options are empty on purpose: the graph inspector fills in the behavior's variables. */
-export const variableParam: PropertyDef = { key: 'variable', label: 'Variable', kind: 'enum', default: '', options: [] };
+export const variableParam: PropertyDef = {
+  key: 'variable',
+  label: 'Variable',
+  kind: 'enum',
+  default: '',
+  options: [],
+};
 
 /** Options are empty on purpose: the graph inspector fills in the project's placeable assets. */
-export const assetParam: PropertyDef = { key: 'asset', label: 'Asset', kind: 'enum', default: '', options: [] };
+export const assetParam: PropertyDef = {
+  key: 'asset',
+  label: 'Asset',
+  kind: 'enum',
+  default: '',
+  options: [],
+};
 
 // --- node factories --------------------------------------------------------------------------
 
@@ -59,7 +76,11 @@ export function unaryMath(type: string, description: string, fn: (value: number)
 }
 
 /** A data node combining the booleans `a` and `b`. */
-export function binaryLogic(type: string, description: string, fn: (a: boolean, b: boolean) => boolean): NodeDef {
+export function binaryLogic(
+  type: string,
+  description: string,
+  fn: (a: boolean, b: boolean) => boolean,
+): NodeDef {
   return {
     type,
     label: type,