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>

tools/seed-e2e.mjs

@@ -61,7 +61,12 @@ const project = {
       props: { backgroundColor: 0x22252c },
       objects: [
         sceneObject('o1', 'crate', { x: -150 }),
-        sceneObject('o2', 'crate', { name: 'Blue crate', x: 120, y: -80, overrides: { width: 140, color: 0x4488ff } }),
+        sceneObject('o2', 'crate', {
+          name: 'Blue crate',
+          x: 120,
+          y: -80,
+          overrides: { width: 140, color: 0x4488ff },
+        }),
         sceneObject('o3', 'cam'),
         // The Mover is parented to the red crate (its owner); its position is local to it.
         sceneObject('o4', 'mover', { y: 110, parentId: 'o1' }),
@@ -75,8 +80,20 @@ const project = {
     },
     { id: 'crate', type: 'sprite', name: 'Crate', props: { width: 100, height: 60, color: 0xe0553f } },
     { id: 'cam', type: 'camera', name: 'Main camera', props: { width: 640, height: 360, zoom: 1 } },
-    { id: 'collider', type: 'collider', name: 'Crate collider', props: { shape: 'box', width: 100, height: 60, radius: 50, isTrigger: false } },
-    { id: 'mover', type: 'behavior', name: 'Mover', props: { speed: 200 }, variables: [variable('speed', 'number', 0)], graph: moverGraph },
+    {
+      id: 'collider',
+      type: 'collider',
+      name: 'Crate collider',
+      props: { shape: 'box', width: 100, height: 60, radius: 50, isTrigger: false },
+    },
+    {
+      id: 'mover',
+      type: 'behavior',
+      name: 'Mover',
+      props: { speed: 200 },
+      variables: [variable('speed', 'number', 0)],
+      graph: moverGraph,
+    },
     { id: 'spawner', type: 'behavior', name: 'Spawner', props: {}, variables: [], graph: spawnerGraph },
   ],
 };