feat: festive Chinese red background and prize config unification

- Change all big screen backgrounds to pure Chinese red (#c41230)
- Remove vignette effect for consistent display on different screens
- Unify all prize data to match prizes.json configuration
- Add demo participants fallback when no data imported
- Fix particle visibility reset in startGalaxy()

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

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

@@ -2,7 +2,7 @@ import { Application, Container, Graphics, Ticker } from 'pixi.js';
 
 // Cinematic color palette
 const COLORS = {
-  wineRed: 0x2a0a0e,
+  wineRed: 0xc41230, // Festive bright Chinese red
   gold: 0xf0c239,
   goldDark: 0xd4a84b,
   goldLight: 0xffd700,
@@ -81,24 +81,8 @@ export class BackgroundEffect {
   }
 
   private drawVignette(): void {
-    const vignette = new Graphics();
-    const w = this.app.screen.width;
-    const h = this.app.screen.height;
-    const cx = w / 2;
-    const cy = h / 2;
-    const maxRadius = Math.sqrt(cx * cx + cy * cy);
-
-    // Create radial gradient effect with multiple circles
-    for (let i = 20; i >= 0; i--) {
-      const ratio = i / 20;
-      const radius = maxRadius * (0.3 + ratio * 0.7);
-      const alpha = ratio * 0.8;
-
-      vignette.circle(cx, cy, radius);
-      vignette.fill({ color: 0x000000, alpha });
-    }
-
-    this.app.stage.addChildAt(vignette, 0);
+    // Disabled vignette for pure solid color background
+    // Keep method for potential future use
   }
 
   private initDustParticles(): void {

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

@@ -11,7 +11,7 @@ const COLORS = {
   red: 0xc21f30,
   redLight: 0xe63946,
   redDark: 0x8b0000,
-  wineRed: 0x2a0a0e,
+  wineRed: 0xc41230, // Festive bright Chinese red
   black: 0x000000,
   white: 0xffffff,
 };
@@ -245,9 +245,13 @@ export class LotteryMachine {
     this.confettiContainer.removeChildren();
     this.dimOverlay.clear();
 
-    // Reset particles
+    // Reset particles - restore visibility
     this.nameParticles.forEach((p) => {
       p.isWinner = false;
+      if (p.text) {
+        p.text.visible = true;
+        p.text.alpha = 1;
+      }
     });
 
     this.phase = 'galaxy';