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).

server/sim/content/kits/tier5.js

@@ -893,8 +893,8 @@ const KITS = {
               for (const a of unit.mem.sickles || []) {
                 if (!a.alive || !a.deployed) continue;
                 // PRTS 备注 "被添加血镰的单位处于起飞时，血镰可对空": a sickle on the ground spares air units (FLY, 近地悬浮, 浮空);
-                // 起飞 = an airborne skywalker (蒂比's skill: off the ground, flag blockFly)
-                const air = !a.ground && !!a.s.flags.blockFly;
+                // 起飞 = an airborne skywalker (蒂比's skills: flag `liftoff`; still a 地面单位, so she can carry one)
+                const air = !!a.s.flags.liftoff;
                 for (const e of battle.enemiesInRadius(a.x, a.y, RING1)) {
                   if (e.isFlying && !air) continue;
                   battle.dealDamage(unit, e, { amount: unit.s.atk * num(bb.atk_scale), type: 'phys', isSkill: true, tags: ['skill', 'bloodSickle'] });