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/GraphInterpreter.ts

@@ -41,7 +41,12 @@ export class GraphInterpreter {
    * Fires every event node of `type` whose params satisfy `filter`, seeding its outputs with
    * `outputs` (e.g. `{ dt }`). Returns how many event nodes fired.
    */
-  fire(type: string, ctx: NodeContext, outputs: Record<string, Value> = {}, filter?: (node: GraphNode) => boolean): number {
+  fire(
+    type: string,
+    ctx: NodeContext,
+    outputs: Record<string, Value> = {},
+    filter?: (node: GraphNode) => boolean,
+  ): number {
     let fired = 0;
     for (const node of this.eventNodes(type)) {
       if (filter && !filter(node)) continue;
@@ -66,7 +71,8 @@ export class GraphInterpreter {
   }
 
   private execute(node: GraphNode, ctx: NodeContext): void {
-    if (++this.steps > MAX_STEPS_PER_FIRE) throw new Error('Behavior graph exceeded the step limit (infinite loop?)');
+    if (++this.steps > MAX_STEPS_PER_FIRE)
+      throw new Error('Behavior graph exceeded the step limit (infinite loop?)');
     const def = requireNodeDef(node.type);
     if (!def.run) return;
     const inputs = this.collectInputs(node, ctx);
@@ -99,7 +105,8 @@ export class GraphInterpreter {
     const def = requireNodeDef(source.type);
     // Exec nodes that have not run in this pulse have no value yet.
     if (isEventNode(def) || hasExecInput(def) || !def.run) return null;
-    if (++this.steps > MAX_STEPS_PER_FIRE) throw new Error('Behavior graph exceeded the step limit (data cycle?)');
+    if (++this.steps > MAX_STEPS_PER_FIRE)
+      throw new Error('Behavior graph exceeded the step limit (data cycle?)');
     // Mark before evaluating so a data cycle reads null instead of recursing forever.
     this.outputCache.set(nodeId, {});
     const outputs = def.run(ctx, this.collectInputs(source, ctx), source.params).outputs ?? {};