USB wording: a USB 2.0 type-A plug on the way; hubs are fine

Guide, README, quick start and flashing hints no longer say 'no hub' or 'directly to the laptop'; the requirement is a USB 2.0 type-A plug between box and computer (USB-C only is the failing case).

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

kota_tech/ui/flash_tab.py

@@ -36,7 +36,7 @@ BACKUP_DIR = SESSIONS_DIR.parent / "backups"
 VERIFY_TIMEOUT_MS = 45_000
 
 HELP = (
-    "<b>If flashing cannot connect:</b> use a data-capable USB cable directly on the laptop, close "
+    "<b>If flashing cannot connect:</b> use a data-capable cable with a USB 2.0 type-A plug on the way, close "
     "other programs using the port, then retry. Last resort (case must be opened): hold <b>BOOT</b>, "
     "press and release <b>RESET</b>, release <b>BOOT</b>, and press Start again."
 )