feat: replacement effects in Module 4 (Armor absorption, Bolf Ramshield redirect)

Applying a Damage to one target now runs DAMAGE_STEPS = [redirect, armor]
first. A damageRedirect aura (Bolf Ramshield, fetched from the wiki) sends
damage meant for its owner's hero to the oldest such minion; Armor absorbs
damage to a hero before Health, logged as the new ArmorLost{player, amount}
just before a full-amount Damaged. Four new Module 4 tests; propagated to the
references of Modules 4-10 in both tracks; card schema, catalog, card JSON,
harness.md, Lessons 2, 4 and 5 updated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

course/08-push-chains/reference/ts/src/engine/event.ts

@@ -11,6 +11,8 @@ export type Event =
   | { type: "Drew"; player: PlayerId; id: EntityId }
   | { type: "Fatigue"; player: PlayerId }
   | { type: "ArmorGained"; player: PlayerId; amount: number }
+  /** Armor absorbed `amount` of a Damage to `player`'s hero. The `Damaged` that follows shows the full amount. */
+  | { type: "ArmorLost"; player: PlayerId; amount: number }
   | { type: "StatsChanged"; id: EntityId; attack: number; health: number }
   | { type: "SpellCast"; card: string }
   /**