UX S6: race truth-up — wire Tiefling fire resist + best-fit hints

R22: replace race copy that promised mechanics the engine doesn't deliver.
- Tiefling: wire FireResist as a CombatModifier. Enemy main attack is
  halved when monster is FireAttacker-tagged; aoe_fire abilities are
  halved unconditionally; fire-tagged traps deal half damage to Tieflings.
  DnDMonsterTemplate carries FireAttacker; toCombatStats propagates it.
  Hand-authored fire entries tagged in dnd_bestiary.go (flameskull,
  magmin, azer, salamander, fire_elemental, emberlord_thyrak,
  young_red_dragon, infernax, belaxath).
- Open5e tuned generator derives FireAttacker from the highest-AvgDamage
  attack's DamageType (threshold AvgDamage>=5). 19 tuned monsters tag.
  Regenerated bestiary_tuned_data.go.
- Elf: drop "immune to sleep" (no sleep mechanic); reframe as keen
  senses + trance flavor.
- Half-Elf: drop "two bonus skill proficiencies" (no skill system);
  reframe as adaptable cross-cultural know-how.
- Tiefling copy: drop "bonus on CHA checks" (no checks); keep fire
  resistance with flavor framing.

R23: DnDRaceInfo grows a BestFit field; renderRaceMenu emits an
"_best with: …_" hint per race so spiky stat spreads (Orc -1/-1/-1)
read as specialist picks rather than a brick of penalties.

R24: dnd.go header comment for the caster classes now reflects the
shipped state (Playable=true, spell lists populated) instead of the
pre-Open5e scaffold language.

Tests: TestApplyRacePassives gains a FireResist column; new
TestTieflingFireResistance asserts ~0.5x ratio over a 300-trial sweep
against a FireAttacker enemy. Full suite green.

internal/plugin/combat_engine.go

@@ -36,6 +36,13 @@ type CombatStats struct {
 	AbilityModForDamage int
 	WeaponProficient    bool // false → -4 attack penalty (appendix §8 implementation note)
 	TwoHandedMode       bool // true + versatile weapon → use larger versatile die
+
+	// FireAttacker tags monsters whose signature damage is fire (red dragons,
+	// fire elementals, hell hounds, magmin, balor, …). The enemy-attack path
+	// halves incoming damage when this is set on the enemy and FireResist is
+	// set on the player. Carried via toCombatStats; tuned generator derives it
+	// from SRD attack DamageType; hand-authored entries set it explicitly.
+	FireAttacker bool
 }
 
 type CombatModifiers struct {
@@ -71,6 +78,7 @@ type CombatModifiers struct {
 	LuckyReroll  bool // Halfling: reroll the first nat 1 of the fight
 	RageReady    bool // Orc: when HP first drops <50%, next attack deals +50% damage
 	PoisonResist bool // Dwarf: poison tick damage halved
+	FireResist   bool // Tiefling: incoming damage from fire-tagged sources halved
 
 	// Phase 10 SUB2a — subclass combat hooks.
 	// CritThreshold: lowest d20 roll that crits. 0 = use default (20).
@@ -910,6 +918,13 @@ func resolveEnemyAttack(st *combatState, player, enemy *Combatant, phase *Combat
 	if player.Mods.BerserkerRage && player.Mods.PhysicalResistRage {
 		dmg = max(1, dmg/2)
 	}
+	// Tiefling fire resistance — halve the enemy's primary attack when the
+	// monster's signature damage is fire (FireAttacker, set on the template).
+	// Aligned with the Berserker pattern: applied after crit-doubling so the
+	// resistance survives a nat 20.
+	if player.Mods.FireResist && enemy.Stats.FireAttacker {
+		dmg = max(1, dmg/2)
+	}
 	dmg = max(1, dmg)
 
 	if petDeflect {
@@ -1093,6 +1108,16 @@ func applyAbility(st *combatState, player, enemy *Combatant, phase *CombatPhase,
 		// An area burst that partly bypasses armor (defWeight cut to 0.4), so a
 		// high-defense build still feels it. Rider on top of the normal attack.
 		dmg := abilityHitDamage(st, player, enemy, phase, 0.7, 0.4)
+		// Tiefling fire resistance: the aoe_fire effect name encodes a fire
+		// burst (Burning Hands, Fireball, Fire Breath). Halve for FireResist.
+		// Generic "aoe" / "death_aoe" don't always carry fire damage, so we
+		// gate on the effect string — the FireAttacker flag on the monster
+		// covers fire-themed creatures whose death/aura uses a non-aoe_fire
+		// effect (e.g., magmin's death_aoe burst rides their FireAttacker tag
+		// via the primary-attack halving path).
+		if ab.Effect == "aoe_fire" && player.Mods.FireResist {
+			dmg = max(1, dmg/2)
+		}
 		st.playerHP = max(0, st.playerHP-dmg)
 		st.events = append(st.events, CombatEvent{
 			Round: st.round, Phase: phaseName, Actor: "enemy", Action: "aoe",