feat: skill cooldown (3/combat), inventory limit (10), scaled event damage

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

entity/player.go

@@ -35,6 +35,7 @@ type Player struct {
 	Relics      []Relic
 	Dead        bool
 	Fled        bool
+	SkillUses   int // remaining skill uses this combat
 }
 
 func NewPlayer(name string, class Class) *Player {