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/dnd_zone_combat.go

@@ -295,6 +295,10 @@ func (p *AdventurePlugin) applyTrapEffectWithDetect(
 	}
 
 	dmg := rollTrapDamage(trap, run.RunID, run.CurrentRoom)
+	// Tiefling fiendish heritage — fire traps deal half damage.
+	if trap.DamageType == "fire" && dndChar.Race == RaceTiefling {
+		dmg = max(1, dmg/2)
+	}
 	if dmg >= dndChar.HPCurrent {
 		dmg = dndChar.HPCurrent - 1
 		if dmg < 0 {