feat: Full UI internationalization, pool hashrate stats, and layout caching

- Replace all hardcoded English strings with TR() translation keys across
  every tab, dialog, and component (~20 UI files)
- Expand all 8 language files (de, es, fr, ja, ko, pt, ru, zh) with
  complete translations (~37k lines added)
- Improve i18n loader with exe-relative path fallback and English base
  fallback for missing keys
- Add pool-side hashrate polling via pool stats API in xmrig_manager
- Introduce Layout::beginFrame() per-frame caching and refresh balance
  layout config only on schema generation change
- Offload daemon output parsing to worker thread
- Add CJK subset fallback font for Chinese/Japanese/Korean glyphs

src/daemon/xmrig_manager.h

@@ -49,6 +49,8 @@ public:
         int64_t memory_total = 0;   // bytes
         int64_t memory_used  = 0;   // bytes (resident set size)
         int     threads_active = 0; // actual mining threads
+        // Pool-side hashrate (from pool stats API, not xmrig)
+        double pool_hashrate = 0;
     };
 
     /// User-facing config (maps 1:1 to UI fields / Settings)
@@ -138,6 +140,7 @@ private:
     void drainOutput();
     void appendOutput(const char* data, size_t len);
     void fetchStatsHttp();  // Blocking HTTP call — runs on monitor thread only
+    void fetchPoolApiStats();  // Fetch pool-side stats (hashrate) from pool HTTP API
 
     std::atomic<State> state_{State::Stopped};
     std::string last_error_;
@@ -149,6 +152,7 @@ private:
     int         api_port_  = 0;
     std::string api_token_;
     int         threads_   = 0;  // Thread count for mining
+    std::string pool_host_;       // Pool hostname for stats API
     PoolStats   stats_;
     mutable std::mutex stats_mutex_;