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

site/content/guide/updates.md

@@ -9,7 +9,7 @@ screens = ["update.png"]
 
 Every update is one **signed file** (`.ota`). The device installs only a file signed with the project's key, so it cannot be tricked into installing anything else, whichever way the file arrives.
 
-## Settings → Firmware
+## Settings → System → Firmware
 
 The page shows the **version** running, its **status**, the address to **push updates to** over Wi-Fi, and:
 
@@ -21,7 +21,7 @@ An install needs Wi-Fi if it is a download. The new firmware is checked before a
 
 ## Check for updates
 
-**Settings → Check for updates** is on by default. Once a day, with Wi-Fi up and the clock set, the device looks at the latest release and says `v0.11.0 is out: see Settings > Firmware`, once per version. It installs **nothing** by itself, and it does not announce a version that already failed and rolled back on this device.
+**Settings → System → Check for updates** is on by default. Once a day, with Wi-Fi up and the clock set, the device looks at the latest release and says `v0.11.0 is out: see Settings > System > Firmware`, once per version. It installs **nothing** by itself, and it does not announce a version that already failed and rolled back on this device.
 
 ## Probation and Rollback