Fix repeated device enumeration in hardware wallet wizard (Electron-Cash#3192)

choose_hw_device() called unpaired_device_infos() per plugin, and each
call triggered a full scan_devices() across all plugins — creating N²
enumeration calls. Now scan_devices() is called once before the loop
and the cached result is passed via the existing devices= parameter.

Co-authored-by: John Moriarty <JLMoriart@users.noreply.github.com>
Co-authored-by: Claude Opus 4.6 <noreply@anthropic.com>

Author: JLMoriart

electroncash/base_wizard.py

@@ -222,13 +222,14 @@ def choose_hw_device(self):
         title = _('Hardware Keystore')
         # check available plugins
         support = self.plugins.get_hardware_support()
-        # scan devices
+        # scan devices once upfront (not per-plugin) to avoid repeated enumeration
         devices = []
         devmgr = self.plugins.device_manager
+        scanned = devmgr.scan_devices()
         for name, description, plugin in support:
             try:
                 # FIXME: side-effect: unpaired_device_info sets client.handler
-                u = devmgr.unpaired_device_infos(None, plugin)
+                u = devmgr.unpaired_device_infos(None, plugin, devices=scanned)
             except:
                 devmgr.print_exception("error", name)
                 continue