feat(i18n): migrate all hardcoded Russian text to i18n

- Replace all hardcoded Russian strings with t() calls across 30+ files
- Add ~500 new translation keys to all 4 locales (ru, en, zh, fa)
- Convert module-level config objects to labelKey pattern
- Remove Russian fallbacks from t() calls (fallbackLng handles it)
- Replace DeepLinkRedirect custom i18n with standard t() calls
- Fix subscription.servers key collision (string vs object)

src/pages/Contests.tsx

@@ -234,7 +234,7 @@ export default function Contests() {
                 <div className="flex items-center gap-1 text-accent-400">
                   <TrophyIcon />
                   <span className="text-sm font-medium">
-                    +{contest.prize_days} {t('contests.days')}
+                    +{t('contests.days', { count: contest.prize_days })}
                   </span>
                 </div>
               </div>