Store XP packs (expensive), winner 2x XP, premium perks

- XP packs in the store (coin-priced, intentionally expensive): xp1 200/5k,
  xp2 600/12k, xp3 1500/25k. Consumable (grant XP, can level up) — server
  ShopBuy handles kind "xp" via an authoritative XpPacks map + Gamification.GrantXp;
  mock mirrors. New shop section + shop.xp/xpHint i18n.
- Every game grants XP and the WINNER earns 2x: matchXp is now
  base*(won?2:1)*leagueFactor (was a flat +80 win bonus). Mirrored server-side.
- Premium (pro) perks: 1.5x XP multiplier (applied in applyMatchResult /
  ApplyMatch by plan), plus animated shimmering gold chat bubbles for your own
  messages (premium-chat CSS; ChatScreen gates on plan).

Verified: tsc + next + dotnet build clean; sim passes; live server — buying xp2
took L1→L3 and deducted 12k coins under the new curve. Images rebuilt :1500/:1505.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/lib/i18n.tsx

@@ -258,6 +258,8 @@ const fa: Dict = {
   "shop.cardstyles": "طرح کارت‌ها",
   "shop.reactions": "بسته شکلک‌ها",
   "shop.stickers": "بسته استیکرها",
+  "shop.xp": "امتیاز تجربه (XP)",
+  "shop.xpHint": "افزایش سریع سطح — XP گران است",
   "reward.newTitle": "عنوان جدید",
 
   "reactions.title": "شکلک",
@@ -521,6 +523,8 @@ const en: Dict = {
   "shop.cardstyles": "Card styles",
   "shop.reactions": "Reaction packs",
   "shop.stickers": "Sticker packs",
+  "shop.xp": "XP packs",
+  "shop.xpHint": "Level up faster — XP is expensive",
   "reward.newTitle": "New title",
 
   "reactions.title": "Emoji",