feat: enhance lottery system with participant import and prize config

- Fix ES module import issue in admin.service.ts (require -> import)
- Fix lottery reveal ghosting by hiding name particles on complete
- Add participant import from Excel with tag calculation
- Add prize configuration service with JSON persistence
- Constrain winners overlay to scroll area dimensions
- Fix macOS lsof syntax in stop script
- Add HorseRace view and renderer (WIP)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

packages/client-screen/src/pixi/LotteryMachine.ts

@@ -237,6 +237,19 @@ export class LotteryMachine {
    * Start the lottery - transition to Galaxy phase
    */
   startGalaxy(): void {
+    // Clear previous round's reveal display
+    this.winners = [];
+    this.confettiParticles = [];
+    this.revealContainer.removeChildren();
+    this.scrollContainer.removeChildren();
+    this.confettiContainer.removeChildren();
+    this.dimOverlay.clear();
+
+    // Reset particles
+    this.nameParticles.forEach((p) => {
+      p.isWinner = false;
+    });
+
     this.phase = 'galaxy';
     this.phaseTime = 0;
     this.onPhaseChange?.('galaxy');
@@ -542,8 +555,18 @@ export class LotteryMachine {
     // Spawn confetti when reveal is complete
     if (this.revealProgress >= 1 && this.phase === 'reveal') {
       this.phase = 'complete';
+
+      // Hide all name particles to prevent ghosting
+      this.nameParticles.forEach((p) => {
+        if (p.text) {
+          p.text.alpha = 0;
+          p.text.visible = false;
+        }
+      });
+
       this.spawnConfettiBurst();
-      this.createWinnerDisplay();
+      // Don't create Pixi winner display - Vue overlay handles it
+      // this.createWinnerDisplay();
       this.onWinnersRevealed?.(this.winners);
       this.onPhaseChange?.('complete');
     }