refactor: one copy of shared logic and widgets; GPS is asked for, not switched on silently

Duplicates found between the L1 and L2 frontends, and inside the L2 one:
- geo::fmtLocShare / fmtLatLon / turnDeg / isAhead (GeoUtils.h): the [LOC]
  text was built in five places, the turn angle and its "ahead" threshold in
  both navigations, coordinates by hand in nine. Tested.
- LiveShareEngine::setEnabled: live share was switched in three places.
- L1 waypoint share uses WaypointModel::shareText; Trail's "Share my pos"
  goes through UITask::quickShareMyLocation, so it now sends to a running
  live-share session as the home Map page does.
- L2 Widgets.h: switchCreate (one switch size, was four), switchRow with a
  state and callback (16 hand-wired copies), switchRowOpens (Bluetooth, WiFi,
  GPS), primaryButton (one height for Save / Measure / New area / Update).

GPS: with it off, starting the trail, live share or track back, sharing or
marking a position, or centring the map asks first ("GPS is off") on both
L1 and L2; Cancel leaves it undone. A share or a mark waits for a fresh fix
(a switched-off module may still report its last one), which also fixes the
L1 "Share my pos" sending a stale position. SOS still turns the GPS on itself.

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

docs/solo/tools.md

@@ -277,6 +277,11 @@ Right** between them, **Up / Down** scrolls):
 battery; anything that needs your position (the trail, live share, the
 locator) keeps it on.
 
+With the GPS switched off, starting the trail, live share or track back, or
+sharing or marking your position, asks first (**GPS is off**): turning it on
+there starts what you chose; a share or a mark waits for the first fix, as
+the last one may be old. SOS doesn't ask: it turns the GPS on itself.
+
 > [!NOTE]
 > **Wio Tracker L2:** the Diagnostics app, with a **Noise** tab that
 > measures the noise floor over time and history charts you can touch for the