feedback1f WT: 蒂比's 起飞 is 对地规避 — ground enemies no longer target or hit her while airborne

Official: ba.liftoff 起飞 "不阻挡地面敌人且不会被地面敌人攻击，可以阻挡飞行敌人"; PRTS 术语释义 起飞 "包含对地规避（无法被不同
阵营行动方式为地面的单位选中）… 起飞后单位的行动方式依旧是地面"; PRTS 异常效果 MOTION_TARGET_FREE; PRTS 行动方式 "起飞的干员仍然
是地面单位".

Cause: 起飞 was `unit.ground = false` (an operator on a high tile). Melee enemies were released, but every ranged
ground enemy kept shooting her and the AoE / skills of ground enemies hit her (控潮术师 6 hits in one S2 window).

Now 起飞 is the skill buff flag `liftoff`:
- targeting.js evadesGround: no ground enemy (not Unit.isFlying) selects her (canTargetAlly; the content picks that
  bypass it: 周围四格 additions, chain / bounce jumps, the 自行炮 shells); flyers, 近地悬浮 and 浮空 enemies still do.
- damage.js / Battle.applyStatus: a ground enemy's damage, element fill and statuses never land on her (area damage,
  shots under way); sourceless damage and `ignoreSelect` zones (【污染秽蚀】 "可对空，无视无法选择") still do.
- Battle._blockerFor: she blocks no ground enemy; flyers at the air radius as before.
- She stays a ground unit on her low tile: 污染秽蚀 at the low rate, 隐德来希 S2 can put a 血镰 on her (可对空).

test/content/kits_t1t2.test.js

@@ -962,7 +962,8 @@ test('2_13 蒂比: an incoming attack triggers 紧急赶场通知 and is dodged;
   assert.equal(h.hooksOf('skillStart').find((c) => c.unit === u).reason, 'TAKE_DAMAGE');
   assert.equal(u.stats.taken, 0, 'the triggering hit was dodged');
   approx(u.s.atk, u.base.atk * (1 + bb.atk));
-  assert.equal(u.ground, false);
+  assert.equal(u.s.flags.liftoff, true, 'airborne (起飞)');
+  assert.equal(u.ground, true, 'still a ground unit on her low tile');
   h.step();
   assert.equal(e.blockedBy, null, 'airborne: ground enemies are released');
   const fl = h.spawn('f', { pos: [9, 5] });