feedback1 integrate: no status on a 无敌 + 无法选中 unit; 余 S2 skips 自缚 units; 信仰搅拌机 S2 blocks with too few bullets

- Battle.applyStatus: a unit both invulnerable and untargetable takes no status from the
  other side (PRTS 无敌 "无法被不同阵营选中"), so the status carried by the hit that knocks an
  enemy out (妮芙 S2's fear, a 叙拉古 proc) no longer lands after its 重生 cleanse.
- Flag selfBound (自缚: 守墓石像's 转换模式, the 自缚 leaders, the 胄 parts' anchor): 余 S2
  never teleports such a unit (PRTS 余 S2 备注 "持有自缚的单位不视为可达目标").
- 信仰搅拌机 S2: with fewer than ammo_cost bullets the lethal hit is still blocked, every
  bullet goes and the skill ends; it steps aside while 坚固维式重锤's 不死 window holds her
  (PRTS 备注), replacing the [ASSUMED] no-guard rule.

server/sim/buffs.js

@@ -33,6 +33,9 @@ export const FLAG_KEYS = Object.freeze([
   'stun', 'freeze', 'sleep', 'silence', 'disarm', 'stealth', 'invulnerable', 'unblockable', 'levitate', 'fear',
   'cold', 'reveal', 'bind', 'noHeal', 'untargetable', 'blockFly', 'noMove', 'noSp', 'burstLock', 'hidden',
   'noBlock', 'tremble', 'hitCount', 'hitCountArts', 'attract', 'float', 'noDisplace', 'isolated', 'camou',
+  // 自缚 (the unit's own immobility: 守墓石像's 转换模式, the 自缚 leaders) beside its `noMove` — 束缚 sets noMove too, and
+  // only 自缚 makes a unit "不视为可达目标" for 余 S2's teleport (PRTS 余 S2 备注)
+  'selfBound',
 ]);
 
 /**