feedback5 O8: two additive engine rules for the 自选 kits — a 屏障 of one damage type and a profile's own target exclusion

- buffs.js makeBuff / damage.js absorbShields: a shield buff with `shieldType` ('phys' | 'arts' | 'true' | 'elemental')
  absorbs that damage type only (夜莺 S2 法术护盾 "屏障能吸收…法术伤害"); a shield without a type absorbs every type as
  before (PRTS 术语释义 屏障 "若无特殊说明，屏障可吸收全种类伤害"); shields are still spent oldest first.
- targeting.js canTargetEnemy: a profile's `skipEnemy(e)` (a kit trait) keeps such an enemy out of the unit's normal
  targets, its block targets and its skill-trigger target condition (嵯峨 劝善 "嵯峨不攻击重伤单位").
- docs/SIM.md §3 / §4 / §8, professions.js profile field list.
No content uses either yet: golden unchanged (roster 49, bonds 46, fields 22, matches 17, standins 10, diy 6 match).
Test: test/sim/feedback5-o8-engine.test.js (2).

server/sim/professions.js

@@ -21,6 +21,7 @@
 //   noHeal bool (cannot be healed by others)   blockFly bool   onHitStatus {key, duration, value}
 //   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")
 //   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)