fix: fight restart bug, mobile TTS, character sizing, bitcoin symbols

- Fix fight replay showing empty scene: validate rounds before playing,
  retry loading fight data up to 5 times when rounds are missing
- Add COOP/COEP headers to production server for SharedArrayBuffer
  (required by Kokoro TTS WASM threading on mobile)
- Add blob: to scriptSrc/workerSrc CSP for Web Worker support
- Fix mobile character cutoff: raise ground line to 0.82, add
  MOBILE_SCALE_CAP (0.55) so fighters never shrink too small
- Add ₿ bitcoin chest badge to all fighter sprites (scales with tier)
- Add sats coin stack on bot profile page proportional to satsWon
- Seed dev tournament with 8 mock bots on startup (dev mode only)

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

frontend/src/game/FightScene.ts

@@ -9,7 +9,7 @@ import { pickChoreography } from './fight/choreography/picker'
 export { pickChoreography }
 import {
   isPerfMode, perfParticles, isReducedMotion, haptic,
-  GROUND_Y_RATIO, HOME_A_RATIO, HOME_B_RATIO, REFERENCE_HEIGHT, SPRITE_LOAD_TIMEOUT_MS,
+  GROUND_Y_RATIO, HOME_A_RATIO, HOME_B_RATIO, REFERENCE_HEIGHT, MOBILE_SCALE_CAP, SPRITE_LOAD_TIMEOUT_MS,
   FIGHTER_BASE_SCALE, FIGHTER_TIER_SCALE, JUDGE_SCALE, HUMAN_COACH_SCALE, HUMAN_RUN_SCALE,
   AMBIENT_PARTICLE_COUNT, SKY_GRADIENT_BANDS, GROUND_DEPTH_LINES, PERSPECTIVE_GRID_LINES, PILLAR_WIDTH,
   SPEECH_BUBBLE_MAX_CHARS, SPEECH_BUBBLE_WRAP, SPEECH_BUBBLE_MAX_LINES, SPEECH_BUBBLE_FONT_SIZE, SPEECH_BUBBLE_DEFAULT_DURATION,
@@ -193,7 +193,7 @@ export async function createFightScene(config: FightSceneConfig) {
   const vhsTracking = (duration: number = 0.4) => _vhsTracking(fightCtx, duration)
   const dimensionalShift = (duration: number = 0.6) => _dimensionalShift(fightCtx, duration)
 
-  const SF = Math.min(1, H / REFERENCE_HEIGHT)
+  const SF = Math.max(MOBILE_SCALE_CAP, Math.min(1, H / REFERENCE_HEIGHT))
   const GROUND_Y = H * GROUND_Y_RATIO
   const HOME_A = W * HOME_A_RATIO
   const HOME_B = W * HOME_B_RATIO

frontend/src/game/fight/config.ts

@@ -87,10 +87,11 @@ export const HYPERDETAIL_BASE_CHANCE = 0.05         // Base hyperdetail chance
 export const HYPERDETAIL_INTENSITY_SCALE = 0.45     // Scales with intensity
 
 // --- Scene layout ---
-export const GROUND_Y_RATIO = 0.78                  // Ground line as fraction of canvas height
+export const GROUND_Y_RATIO = 0.82                  // Ground line as fraction of canvas height
 export const HOME_A_RATIO = 0.28                    // Fighter A home X position ratio
 export const HOME_B_RATIO = 0.72                    // Fighter B home X position ratio
 export const REFERENCE_HEIGHT = 500                 // Reference canvas height for scale factor
+export const MOBILE_SCALE_CAP = 0.55                // Cap SF on small screens so fighters aren't too tiny
 export const SPRITE_LOAD_TIMEOUT_MS = 5_000         // Max wait for sprite loading (mobile hang prevention)
 
 // --- Fighter scaling ---

frontend/src/game/sprites/index.ts

@@ -201,14 +201,35 @@ export function generateSpriteSheet(
       if (tier >= 3) { px(cx + hOff, beltY, '#ffd700', ox, oy); px(cx + hOff + 1, beltY, '#ffd700', ox, oy) }
     }
 
-    // Chest emblem (tier 4+)
-    if (tier >= 4) {
+    // ₿ Bitcoin chest badge — every fighter carries the symbol
+    {
       const ey = by + Math.round(bh * 0.3)
-      px(cx + hOff - 1, ey, pal.acc, ox, oy)
-      px(cx + hOff, ey, pal.accLight, ox, oy)
-      px(cx + hOff + 1, ey, pal.acc, ox, oy)
-      px(cx + hOff, ey - 1, pal.acc, ox, oy)
-      px(cx + hOff, ey + 1, pal.acc, ox, oy)
+      const ec = cx + hOff
+      // Tier 0-1: simple orange ₿ dot
+      // Tier 2-3: small ₿ shape (vertical bar + bumps)
+      // Tier 4+: full golden ₿ with glow
+      if (tier >= 4) {
+        // Golden glow behind
+        px(ec - 2, ey, '#ffd70066', ox, oy)
+        px(ec + 2, ey, '#ffd70066', ox, oy)
+        px(ec, ey - 2, '#ffd70066', ox, oy)
+        px(ec, ey + 2, '#ffd70066', ox, oy)
+      }
+      const bc = tier >= 4 ? '#ffd700' : tier >= 2 ? '#ff8c00' : '#ff6600'
+      // Vertical stroke
+      px(ec, ey - 1, bc, ox, oy)
+      px(ec, ey, bc, ox, oy)
+      px(ec, ey + 1, bc, ox, oy)
+      // Right bumps (₿ shape)
+      if (bw >= 6) {
+        px(ec + 1, ey - 1, bc, ox, oy)
+        px(ec + 1, ey + 1, bc, ox, oy)
+      }
+      // Top/bottom serifs
+      if (tier >= 2) {
+        px(ec, ey - 2, tier >= 4 ? '#ffd700' : '#cc7000', ox, oy)
+        px(ec, ey + 2, tier >= 4 ? '#ffd700' : '#cc7000', ox, oy)
+      }
     }
 
     // Shoulder pads (tier 3+)