feedback5 O16: two additive engine rules for the 自选 kits of 机械师 and 凯尔希 — a 屏障 limited to a list of damage types, a healer that heals one ally through its 禁疗

- buffs.js makeBuff / damage.js absorbShields: `shieldType` may be a list of damage types — the shield absorbs those only
  (机械师's 屏障 absorb physical and arts damage, not true: buff_template_data mcnist_t_2 / mcnist_s_2_shield BlockDamage
  PHYSICAL_AND_MAGICAL); a single type and an untyped shield work as before.
- damage.js heal / Battle.injuredAlliesInKeys: a healer profile's `healThrough(healer, ally)` names allies its heals reach
  through their 禁疗 (the `noHeal` flag of a summon's 禁疗, the `healFree` flag; a profile `noHeal` — 无法被友方治疗 — still
  stops it), and its heal selection takes them (凯尔希 on her Mon3tr: PRTS Mon3tr(凯尔希的召唤物) "持有禁疗（可被凯尔希…
  无视）"; her charpack attack `_ignoreHealFree`); every other healer still skips them.
- docs/SIM.md §3 / §4 / §8, professions.js profile field list.
No content uses either yet: golden unchanged.
Test: test/sim/feedback5-o16-engine.test.js (2).

server/sim/professions.js

@@ -22,6 +22,8 @@
 //   dmgMul(battle, unit, target) → number      afterHit(battle, unit, target, {dealt,x,y})
 //   canAttack(battle, unit) → bool             afterAttack(battle, unit, targets)
 //   skipEnemy(enemy) → bool (an enemy the unit never selects — targeting.js canTargetEnemy; 嵯峨 "不攻击重伤单位")
+//   healThrough(healer, ally) → bool (a healer that selects and heals that ally through its 禁疗 — Battle
+//                             injuredAlliesInKeys, damage.js heal; 凯尔希 on her Mon3tr)
 //   hitsFn(battle, unit) → n                   install(battle, unit) — per-unit hooks, called once at setup
 //   dollNoAttack bool (傀儡师: its <替身> makes no normal attack and casts no skill — 归溟幽灵鲨, kit trait)
 //   tb — the unit's trait blackboard (data `trait.bb`), used for tunables (module upgrades included on elites)