Give the Fly App GO 4-style obstacle radar, on-screen sticks, AirSense and fly zones

Vision radar: graded obstacle sectors around the centre of the video,
the nearest distance per side, the obstacle overhead, and BLOCKED on a
side whose sensors cannot see once the motors run. On aircraft with 360°
sensing, sides without their own readings are filled from the
perception ring. The same sectors sit on the attitude ball's rim, turned
by the heading. Settings > Vision gains Display radar chart and the
braking / sensing distances per direction.

On-screen sticks: the rail's STICKS button hands the aircraft to two
stick pads after a slide-to-confirm. The 25 Hz stream runs natively and
sends zeros once Dart's last command is 300 ms old, so a stalled UI
leaves the aircraft hovering. The sticks close when the remote takes
over, on RTH or on landing. They are simulator-only on aircraft with a
remote unless Settings > General > Developer allows real flights; Spark
and Mavic Air on Wi-Fi may fly them for real. Which MSDK axis is forward
in velocity + body mode is coded from DJI's documentation and must be
checked in the simulator first.

AirSense: a banner for manned aircraft at warning level 2 and up, with
distance, direction and ICAO code; the planes on the map; the full list
in a sheet and Settings > Safety; and the aircraft's own avoidance
action with its countdown.

Fly zones: DJI GEO zones around the aircraft (or the phone) on the map
with their height limits, a banner for FlySafe notices and in/near-zone
states, take-off refused in restricted and locked authorization zones,
self-unlock of authorization zones, the aircraft's licences (enable,
sync from the DJI account, remove all; ground only), and the GEO
database version with an update button.

Tested with unit and widget tests and screenshot renders only; nothing
has run on an aircraft or the simulator yet.

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

Fly App/lib/ui/fly/left/action_rail.dart

@@ -17,7 +17,7 @@ import '../hud_kit.dart';
 /// The grid toggle that used to sit last lives in the camera menu (Other →
 /// Grid): a fourth button would reach the minimap on a phone.
 class ActionRail extends StatelessWidget {
-  const ActionRail({super.key, required this.model, required this.flow, required this.onModes, this.modeActive = false});
+  const ActionRail({super.key, required this.model, required this.flow, required this.onModes, this.modeActive = false, this.trailing});
 
   final FlightModel model;
   final FlightCommandFlow flow;
@@ -28,6 +28,9 @@ class ActionRail extends StatelessWidget {
   /// A mode's editor is open (the IFM button lights up).
   final bool modeActive;
 
+  /// A small control under the buttons (plan P8: the STICKS toggle).
+  final Widget? trailing;
+
   static ({String icon, String label, Color color}) _look(FlightCommand c) => switch (c) {
         FlightCommand.takeOff => (icon: 'takeoff', label: 'TAKE OFF', color: Glass.accent),
         FlightCommand.land => (icon: 'land', label: 'LAND', color: Glass.pillStrong),
@@ -76,6 +79,7 @@ class ActionRail extends StatelessWidget {
                 onTap: onModes,
               ),
             ),
+          if (trailing != null) Padding(padding: const EdgeInsets.only(top: 2), child: trailing),
         ]);
       },
     );