feat: botfights v1 — full fighting game with Kaplay engine

- Vue 3 + Vite + Tailwind 4 frontend with synthwave aesthetic
- Hono backend on port 9100 with SQLite/Drizzle
- Procedural pixel-art sprite generator (48x48, 8 animation states)
- Kaplay fight scene with punch/kick/special/knockback/KO animations
- 12 mock bots across 6 tiers with Elo rating system
- 9 challenge types, 10 fight arenas with modifiers
- Fight replay with staggered battle log and ~1 min timing
- Sprite preview page at /sprites

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

server/src/engine/events.ts

@@ -0,0 +1,41 @@
+type Listener = (event: FightEvent) => void
+
+export interface FightEvent {
+  fightId: string
+  type: string
+  data: Record<string, unknown>
+  timestamp: string
+}
+
+class EventBus {
+  private listeners = new Map<string, Set<Listener>>()
+  private globalListeners = new Set<Listener>()
+
+  on(fightId: string, listener: Listener) {
+    if (!this.listeners.has(fightId)) {
+      this.listeners.set(fightId, new Set())
+    }
+    this.listeners.get(fightId)!.add(listener)
+    return () => this.off(fightId, listener)
+  }
+
+  onAll(listener: Listener) {
+    this.globalListeners.add(listener)
+    return () => this.globalListeners.delete(listener)
+  }
+
+  off(fightId: string, listener: Listener) {
+    this.listeners.get(fightId)?.delete(listener)
+  }
+
+  emit(event: FightEvent) {
+    this.listeners.get(event.fightId)?.forEach(fn => fn(event))
+    this.globalListeners.forEach(fn => fn(event))
+  }
+
+  cleanup(fightId: string) {
+    this.listeners.delete(fightId)
+  }
+}
+
+export const fightEvents = new EventBus()