feat(engine): board/player constant maps and shared types

src/engine/boards.ts

@@ -0,0 +1,32 @@
+import type { BoardId, Player, Color } from './types';
+
+export const BOARD_IDS: BoardId[] = ['NW', 'NE', 'SW', 'SE'];
+
+/** Turn order. */
+export const PLAYERS: Player[] = ['N', 'S', 'E', 'W'];
+
+/** The two boards each player controls (order is stable: [boardA, boardB]). */
+export const PLAYER_BOARDS: Record<Player, [BoardId, BoardId]> = {
+  N: ['NW', 'NE'],
+  S: ['SW', 'SE'],
+  E: ['NE', 'SE'],
+  W: ['NW', 'SW'],
+};
+
+/** The colour each player plays on both their boards. */
+export const PLAYER_COLOR: Record<Player, Color> = {
+  N: 'w', S: 'w', E: 'b', W: 'b',
+};
+
+/** The white and black player of each board. */
+export const BOARD_PLAYERS: Record<BoardId, { w: Player; b: Player }> = {
+  NW: { w: 'N', b: 'W' },
+  NE: { w: 'N', b: 'E' },
+  SW: { w: 'S', b: 'W' },
+  SE: { w: 'S', b: 'E' },
+};
+
+/** Compass rotation in degrees for rendering each board (see spec §5.1). */
+export const BOARD_ROTATION: Record<BoardId, number> = {
+  NW: 225, NE: 135, SW: 315, SE: 45,
+};