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/editor/graph/NodePalette.ts

@@ -47,8 +47,18 @@ export class NodePalette extends Popup {
   private refresh(): void {
     const query = this.search.value.trim().toLowerCase();
     this.filtered = allNodeDefs()
-      .filter((d) => !query || d.label.toLowerCase().includes(query) || d.type.toLowerCase().includes(query) || d.description.toLowerCase().includes(query))
-      .sort((a, b) => CATEGORY_ORDER.indexOf(a.category) - CATEGORY_ORDER.indexOf(b.category) || a.label.localeCompare(b.label));
+      .filter(
+        (d) =>
+          !query ||
+          d.label.toLowerCase().includes(query) ||
+          d.type.toLowerCase().includes(query) ||
+          d.description.toLowerCase().includes(query),
+      )
+      .sort(
+        (a, b) =>
+          CATEGORY_ORDER.indexOf(a.category) - CATEGORY_ORDER.indexOf(b.category) ||
+          a.label.localeCompare(b.label),
+      );
     this.list.setItems(this.filtered.map((d) => ({ id: d.type, label: d.label, hint: d.category })));
     this.scroll.relayoutContent();
   }