feedback1f WV: a knocked-out operator keeps its tile; 突袭 never lands on it

Player report F5 after 0.1.0: "突袭盟约的干员会移动到濒死干员的尸体上".

Real. A knocked-out operator left the occupancy map at once and only its
home tile stayed reserved. A 突袭 member that fell after its jump lay on the
landing tile, which nothing reserved, so the next member's jump (same target,
same scoring) landed on it; and a member's timed redeploy came back on its home
where a teammate that had jumped there lay. Real matches (six real 突袭
members, 战场#07 / #08, R6 / R9 / R12, 96 battles): 6 placements on a body
(3 jumps, 3 home redeploys) before, 0 of 526 jumps after.

Official (PRTS 卫戍协议/帮助, 作战阶段 / 单位部署):
- "干员退场后…原地留下一个“倒地干员”…满足再部署条件时，移除场上的该倒地干员
  并自动部署至该位置"
- "倒地干员所在地块视为可部署，但所有我方单位在此处的部署行为将被阻止"
- "若干员被击倒的位置为其他干员或召唤物的初始位置，则在被击倒后，尝试返回其
  自身的初始位置"

Now (sim/Battle.js):
- A knocked-out operator lies on `unit.body`: the tile it fell on, or its
  own home when it fell on another board piece's home and its home is free
  (one attempt at the knock-out, assumed). x / y / tileR / tileC keep where
  it fell, so the kill / death handlers still act there.
- Every redeploy comes back there (restTile): the timed one, 不屈's and
  阿戈尔's. A retreated operator still comes back on its home.
- downOn(r, c): _deploy (redeploys, the 突袭 landing, summons), spawnDevice
  and relocate refuse the tile for every ally of the field; isReservedTile
  reports it, so every automatic picker skips it (突袭 raidTile, tactical
  points, summon / device pickers, 维娜's lions). The kit helpers that kept
  their own home-tile loop (tier1 summonTileFree, tier3 / tier4 freeTile) go
  through isReservedTile.
- b.snap `down` entries gain the body tile: [id, respawnAt, respawnTime,
  state, row, col]. DOWN_STATE.WAIT_TILE becomes a safeguard only.

Tests: test/sim/feedback1f-downed-tile.test.js (real Match / PlayerState /
BattleSpec runs with real 突袭 chess, the 突袭 jump, the engine refusals,
the return home); downelem and bonds_addon follow the official rule.

test/sim/downelem.test.js

@@ -1,6 +1,6 @@
 // test/sim/downelem.test.js — user playtest #4 items 8 and 9, sim side (server/sim/Battle.js snapshot / fieldMeta,
-// damage.js elementView): b.snap `down` lists the knocked-out operators waiting to redeploy on their own tile (the
-// client keeps them on the field knocked down with a redeploy countdown) and `elem` the element gauge each unit shows
+// damage.js elementView): b.snap `down` lists the knocked-out operators waiting to redeploy on the tile they lie on (the
+// client keeps them there knocked down with a redeploy countdown) and `elem` the element gauge each unit shows
 // (PRTS 元素: the fullest gauge, its 爆发冷却) — entries, states, and what is left out. User playtest #5 item 2: an
 // operator entering a battle knocked out (联防 carryState `down`, constants.js FORCED_EXIT) is down the same way.
 
@@ -16,7 +16,7 @@ const op = (id, stats = {}) => chessRec({ id, profession: 'WARRIOR', stats: { at
 const TOKEN = { name: '测试召唤物', stats: { maxHp: 100, atk: 0, def: 0, res: 0, blockCnt: 0, cost: 0, respawnTime: 0 } };
 const downOf = (h, id) => (h.snapshot().down || []).find((d) => d[0] === id) || null;
 
-test('a knocked-out operator is `down` until it redeploys: its timer, then waiting for its tile / the DP; then back', () => {
+test('a knocked-out operator is `down` until it redeploys: its timer, then waiting for the DP (no ally takes its tile); then back', () => {
   const h = makeBattle({
     defs: { chess: { t_a: op('t_a'), t_b: op('t_b') } }, units: [{ chessId: 't_a', row: 9, col: 5 }, { chessId: 't_b', row: 10, col: 5 }],
     content: 'none', autoFinish: false, timeLimit: 120, flags: { dpInit: 0, dpPerSec: 1, dpMax: 99 },
@@ -31,18 +31,20 @@ test('a knocked-out operator is `down` until it redeploys: its timer, then waiti
   approx(d[1], Math.round((t0 + 6) * 100) / 100, 0.011);
   approx(d[2], 6, 0.011);
   assert.equal(d[3], DOWN_STATE.COUNTING);
+  assert.deepEqual(d.slice(4), [9, 5], 'the tile it lies on (player report F5 after 0.1.0)');
   assert.ok(h.b.fieldMeta().units.some((u) => u.id === a.id), 'a client joining now gets its UnitInfo');
   h.run(6.5);
   assert.equal(downOf(h, a.id)[3], DOWN_STATE.WAIT_DP, 'timer done, 6.5 DP < cost 12');
-  const tok = h.b.spawnToken('p1', 'token_test', 9, 5, { def: TOKEN });
-  assert.ok(tok && tok.alive, 'a summon stands on its tile');
-  assert.equal(downOf(h, a.id)[3], DOWN_STATE.WAIT_TILE);
-  h.run(7);
-  assert.ok(!a.alive, 'no redeploy while its tile is taken');
-  assert.equal(downOf(h, a.id)[3], DOWN_STATE.WAIT_TILE);
-  h.b.retreat(tok, { reason: 'expired', permanent: true });
-  h.step();
-  assert.ok(a.alive && a.deployed, 'redeployed once the tile is free (DP 13.5 ≥ 12)');
+  // "倒地干员所在地块视为可部署，但所有我方单位在此处的部署行为将被阻止" (PRTS 卫戍协议/帮助): WAIT_TILE (its tile taken)
+  // is a safeguard only — no summon (or any ally) is deployed on the tile it lies on
+  assert.equal(h.b.spawnToken('p1', 'token_test', 9, 5, { def: TOKEN }), null, 'no summon on its tile');
+  assert.equal(h.b.isReservedTile(9, 5), true);
+  h.run(5);
+  assert.ok(!a.alive, 'no redeploy while the DP is short (11.5 < 12)');
+  assert.equal(downOf(h, a.id)[3], DOWN_STATE.WAIT_DP);
+  h.run(1);
+  assert.ok(a.alive && a.deployed, 'redeployed on its tile once the DP is there (12.5 ≥ 12)');
+  assert.deepEqual([a.tileR, a.tileC], [9, 5]);
   assert.equal(downOf(h, a.id), null);
   assert.equal(h.snapshot().down, undefined);
   assert.ok(h.eventsOf('deploy').some((e) => e[1] === a.id));