Combat: fix wounded-carry HP display + auto-crit narration

Two bugs reported back-to-back from a Rogue's run:

1. HP display reset between battles. End of fight 1: 101/123 → start of
   fight 2: 100/100. applyDnDHPScaling was overwriting Stats.MaxHP with
   the scaled wound value, so the display denominator dropped along with
   the numerator. Wounded carry-over became invisible.

   Fix: introduce CombatStats.StartHP. Combat engine reads it as the
   entry-HP when set; MaxHP stays put. Display now reads "100/123" as
   intended.

2. Auto-crit fired on a roll of 11 with no narrative tell. Rogue passive
   AutoCritFirst was triggering correctly, but the renderer used the
   generic crit pool, so the player saw "🎲 11 vs AC 10 → CRIT" with no
   indication their *class* caused it.

   Fix: tag the crit event with Desc="auto_crit" when the passive (not
   the dice) caused it; new narrativePlayerAutoCrit pool calls out the
   training/instinct/exploit theme.

Test bound for T5 dungeon death rate loosened from 0.02 to 0.01 — the
new Sudden Death phase from the previous commit shifted geared-T5
fights slightly toward player wins.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

internal/plugin/dnd_combat.go

@@ -433,13 +433,15 @@ func applyDnDHPScaling(stats *CombatStats, c *DnDCharacter) {
 	if scaled < 1 {
 		scaled = 1
 	}
-	// Defensive: pct is clamped above to [floor, 1.0], so scaled should
-	// always be ≤ original MaxHP. Belt-and-suspenders in case the floor
-	// or pct math drifts in a future refactor.
 	if scaled > stats.MaxHP {
 		scaled = stats.MaxHP
 	}
-	stats.MaxHP = scaled
+	// Set StartHP rather than overwriting MaxHP. The combat engine reads
+	// StartHP as the entry-HP, but display denominators (e.g. "101/123")
+	// keep using MaxHP — so wounded carry-over reads "wounded out of full"
+	// rather than "full out of shrunk-max", which previously made wound
+	// state invisible across battles.
+	stats.StartHP = scaled
 }
 
 // ── HP persistence ───────────────────────────────────────────────────────────