Settings: its rows in five groups

Settings had grown to 21 rows in one list. It opens on five groups (This
device, Display, GNSS and radio, Network, System); Enter opens one, Back
returns to the groups, and Back from the groups leaves Settings.

SettingsMenu holds the groups and which one is open (host-tested: every
setting is in exactly one group). The guide, the how-tos, the README,
the scripts' messages and the firmware's own name the new paths, such as
"Settings > System > Firmware".

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_0162FokPdvY2KsS4NBfwyWPk

scripts/ota_push.py

@@ -2,7 +2,7 @@
 """Pushes a signed Update File to a Cardputer over Wi-Fi (TCP 3232) and reports the result.
 
 Usage: scripts/ota_push.py <file.ota> <host>
-<host> is the device's IP (shown in Settings > Firmware).
+<host> is the device's IP (shown in Settings > System > Firmware).
 """
 import socket
 import sys