Loop over a list and stop at the first match with For each (#249)

Finding the first item that matches took Count, Repeat, Item at and a
Branch, and the loop could not stop once it had found something. A graph
has no lambdas, so the predicate is an input that is read every round.

- For each runs body once per element, with item and index set, and
  goes on at done.
- Its break input is read anew before every round, after item is set.
  Once it is true the loop ends there and that round's body does not
  run.
- done sees the matching item and index with stopped true. Without a
  match it sees no item, index -1 and stopped false, the OrDefault.
- RepeatResult has optional items, stopWhen, stopped and exhausted.
  GraphInterpreter.loop reads them, Repeat runs as before.

Tests:
- ./check.sh: 180 files, 2623 tests, CHECK EXIT 0
- e2e GM_STEPS=1-6: ALL PASSED, 269 checks
- 5 interpreter tests in graph.test.ts, 2 catalog cases
- e2e 6z-iv: the palette creates the node, and a search for
  Name == "Gold" in Axe, Gold, Bow, Gold logs "1true"
- Counter-checks: without the break check 2 unit tests fail, and with
  break not read over its edge 6z-iv fails
- This commit alone: tsc and the three touched unit files pass
  (349 tests)

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/core/graph/NodeRegistry.ts

@@ -42,6 +42,17 @@ export interface RepeatResult {
   port: string;
   index: string;
   times: number;
+  /** Round i also sets output `port` to `values[i]` – the element a `For each` is at. */
+  items?: { port: string; values: readonly Value[] };
+  /**
+   * Boolean input read anew before every round, after the round's outputs are set. True ends the
+   * loop there: that round's body does not run, and its outputs stay for what follows.
+   */
+  stopWhen?: string;
+  /** Boolean output telling whether `stopWhen` ended the loop. */
+  stopped?: string;
+  /** Outputs standing after a loop that ran through all rounds without being stopped. */
+  exhausted?: Record<string, Value>;
 }
 
 /** How a node asks for another behavior's graph to be run in place, `inputs` seeding its start node. */