Fix web flasher reset: use correct esptool.js API

esploader.hardReset() doesn't exist — the correct method is
esploader.after(), which defaults to "hard_reset" mode.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: joined

docs/js/flash.js

@@ -214,7 +214,7 @@ function initFlash() {
       await esploader.writeFlash(flashOptions);
 
       log("Resetting device...");
-      await esploader.hardReset();
+      await esploader.after();
 
       setProgress("Done!", 100);
       log("Flash complete! Device has been reset and should be booting.");