daemon version check, idle mining control, bootstrap mirror, import key paste, and cleanup

- Add startup binary version checking for dragonxd/xmrig
- Display daemon version in UI
- Add idle mining thread count adjustment
- Add bootstrap mirror option (bootstrap2.dragonx.is) in setup wizard
- Add paste button to import private key dialog with address validation
- Add z-address generation UI feedback (loading indicator)
- Add option to delete blockchain data while preserving wallet.dat
- Add font scale slider hotkey tooltip (Ctrl+Plus/Ctrl+Minus)
- Fix Windows RPC auth: trim \r from config values, add .cookie fallback
- Fix connection status message during block index loading
- Improve application shutdown to prevent lingering background process

src/app.h

@@ -253,6 +253,7 @@ public:
     bool isUsingEmbeddedDaemon() const { return use_embedded_daemon_; }
     void setUseEmbeddedDaemon(bool use) { use_embedded_daemon_ = use; }
     void rescanBlockchain();  // restart daemon with -rescan flag
+    void deleteBlockchainData();  // stop daemon, delete chain data, restart fresh
 
     // Get daemon memory usage in MB (uses embedded daemon handle if available,
     // falls back to platform-level process scan for external daemons)
@@ -571,6 +572,7 @@ private:
 
     // Mine-when-idle: auto-start/stop mining based on system idle state
     bool idle_mining_active_ = false;  // true when mining was auto-started by idle detection
+    bool idle_scaled_to_idle_ = false; // true when threads have been scaled up for idle
 
     // Private methods - rendering
     void renderStatusBar();