Stage 7 (wip): tests + UI CI

- Vitest units: board replay, placement machine, premium parity, i18n key parity, FlatBuffers codec round-trips (19 tests)
- Playwright smoke (mock transport): guest -> lobby -> board -> place tile -> preview
- ui-test.yaml workflow: check/unit/build + bundle-size budget (67.5KB gzip < 100KB) + chromium e2e
- gateway transcode tests for games.list (seat display_name), pass, hint
- backend integration test for game.ListForAccount

ui/src/lib/board.test.ts

@@ -0,0 +1,57 @@
+import { describe, expect, it } from 'vitest';
+import { lastPlayTiles, replay } from './board';
+import type { MoveRecord } from './model';
+
+function play(tiles: { row: number; col: number; letter: string; blank: boolean }[]): MoveRecord {
+  return {
+    player: 0,
+    action: 'play',
+    dir: 'H',
+    mainRow: tiles[0].row,
+    mainCol: tiles[0].col,
+    tiles,
+    words: [],
+    count: 0,
+    score: 0,
+    total: 0,
+  };
+}
+
+const pass: MoveRecord = {
+  player: 1,
+  action: 'pass',
+  dir: '',
+  mainRow: 0,
+  mainCol: 0,
+  tiles: [],
+  words: [],
+  count: 0,
+  score: 0,
+  total: 0,
+};
+
+describe('board replay', () => {
+  it('places play tiles and ignores non-play moves', () => {
+    const moves = [
+      play([
+        { row: 7, col: 7, letter: 'A', blank: false },
+        { row: 7, col: 8, letter: 'B', blank: true },
+      ]),
+      pass,
+      play([{ row: 8, col: 7, letter: 'C', blank: false }]),
+    ];
+    const b = replay(moves);
+    expect(b[7][7]?.letter).toBe('A');
+    expect(b[7][8]?.blank).toBe(true);
+    expect(b[8][7]?.letter).toBe('C');
+    expect(b[0][0]).toBeNull();
+    expect(b.length).toBe(15);
+    expect(b[0].length).toBe(15);
+  });
+
+  it('lastPlayTiles returns the most recent play, skipping passes', () => {
+    const moves = [play([{ row: 7, col: 7, letter: 'A', blank: false }]), pass];
+    expect(lastPlayTiles(moves)).toHaveLength(1);
+    expect(lastPlayTiles([pass])).toHaveLength(0);
+  });
+});