Combat: per-round !cast / !consume in turn-based fights

Turn-based Elite/Boss fights gain !cast and !consume as player-turn
actions, so casters and item-users make decisions per round instead of
pre-queuing a single effect. The command handler validates and resolves
the spell/item into a pre-rolled turnActionEffect; the engine just
applies the HP deltas and flows on into the enemy turn.

Scoped to effects that resolve within the casting round: damage, heal,
and control spells, plus heal/flat-damage consumables. Buff and utility
spells and buff-type consumables are refused without spending the
resource — they need cross-round stat persistence, a later sub-phase.

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

internal/plugin/combat_session.go

@@ -55,6 +55,11 @@ type CombatStatuses struct {
 	Enraged       bool    `json:"enraged,omitempty"`
 	ArmorBroken   bool    `json:"armor_broken,omitempty"`
 	ArmorBreakAmt float64 `json:"armor_break_amt,omitempty"`
+	// EnemySkipNext carries a control-spell skip (Hold Person, Sleep) from the
+	// player_turn phase it was cast in to the enemy_turn phase that consumes it
+	// — those phases resolve as separate engine steps with separate in-memory
+	// combatState, so the flag must survive the commit between them.
+	EnemySkipNext bool `json:"enemy_skip_next,omitempty"`
 }
 
 // CombatSession is the in-memory shape of a combat_session row.