Watching a teammate shows their hand, 临时整备区, equipment, strategy and effects (#129)

The prep scout of another player's board carries their 整备区 hand and 临时整备区 as units on the bench rows (like the own prep bench), the equipped items of their operators, their strategy in the drawer and their effects column (the official mode shows a teammate's hand too). The scout signature includes the hand / temp slots, so a moved card refreshes the watcher. Closes #128. Contributed by @2321Robin.

test/match/prep-watch.test.js

@@ -1,7 +1,7 @@
 // GitHub #87: watching another board during prep follows its moves. A spectator uses the same prep scout.
 import { test } from 'node:test';
 import assert from 'node:assert/strict';
-import { PHASE } from '../../shared/constants.js';
+import { GEO, PHASE } from '../../shared/constants.js';
 import { makeMatch, give, legalTileFor, chessOfTier } from './harness.js';
 
 const MELEE = (c) => c.position === 'MELEE' && c.profession === 'TANK';
@@ -31,7 +31,9 @@ test('#87 prep watch: seat B moves during prep and seat A\'s view of B changes b
     const first = h.lastTo(pid, 'm.field');
     assert.equal(first.fieldId, 'n:p_1');
     assert.equal(first.prep, true);
-    assert.equal(first.units.some((u) => u.uid === piece.uid), false, `${pid}: the piece is still in the hand`);
+    const hu = first.units.find((u) => u.uid === piece.uid);
+    assert.ok(hu, `${pid}: the piece is held — it scouts as a unit on the hand row`);
+    assert.equal(hu.y, GEO.HAND_ROW, `${pid}: on the bench (row 7), not on the field`);
   }
   assert.equal(h.allTo(S, 'm.private').length, 0);
   const beforeA = h.allTo('p_0', 'm.field').length;