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/NodeRegistry.ts

@@ -88,7 +88,13 @@ export function inlineInputDef(port: PortDef): PropertyDef {
     case 'any':
       return { key: port.key, label: port.label, kind: 'text', default: asString(port.default ?? '') };
     default:
-      return { key: port.key, label: port.label, kind: 'number', default: asNumber(port.default ?? 0), step: 1 };
+      return {
+        key: port.key,
+        label: port.label,
+        kind: 'number',
+        default: asNumber(port.default ?? 0),
+        step: 1,
+      };
   }
 }