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/control/virtual_stick_pads.dart

@@ -0,0 +1,103 @@
+import 'package:flutter/gestures.dart' show DragStartBehavior;
+import 'package:flutter/material.dart';
+
+import '../../../fly/virtual_sticks.dart';
+import '../../../theme.dart';
+import '../hud_kit.dart';
+
+/// What each pad's axes do in [mode], for the captions under the pads.
+({String left, String right}) stickCaptions(StickMode mode) => switch (mode) {
+      StickMode.mode1 => (left: 'FWD · YAW', right: 'UP · SIDE'),
+      StickMode.mode2 => (left: 'UP · YAW', right: 'FWD · SIDE'),
+      StickMode.mode3 => (left: 'FWD · SIDE', right: 'UP · YAW'),
+    };
+
+/// One on-screen stick (plan P8): a ring the thumb drags a knob inside,
+/// springing back to centre on release like a remote's stick. Reports −1…1
+/// with y up; the drag starts where the finger lands, not after the slop.
+class StickPad extends StatefulWidget {
+  const StickPad({super.key, required this.value, required this.onChanged, required this.caption, this.size = 110});
+
+  final Offset value;
+  final ValueChanged<Offset> onChanged;
+  final String caption;
+  final double size;
+
+  @override
+  State<StickPad> createState() => _StickPadState();
+}
+
+class _StickPadState extends State<StickPad> {
+  double get _radius => widget.size / 2 - 14;
+
+  void _to(Offset local) {
+    final Offset centre = Offset(widget.size / 2, widget.size / 2);
+    widget.onChanged(StickMapper.normalise(local - centre, _radius));
+  }
+
+  @override
+  Widget build(BuildContext context) {
+    final Offset v = widget.value;
+    final Offset knob = Offset(v.dx * _radius, -v.dy * _radius);
+    final bool active = v != Offset.zero;
+    return Column(mainAxisSize: MainAxisSize.min, children: <Widget>[
+      GestureDetector(
+        behavior: HitTestBehavior.opaque,
+        dragStartBehavior: DragStartBehavior.down,
+        onPanStart: (DragStartDetails d) => _to(d.localPosition),
+        onPanUpdate: (DragUpdateDetails d) => _to(d.localPosition),
+        onPanEnd: (_) => widget.onChanged(Offset.zero),
+        onPanCancel: () => widget.onChanged(Offset.zero),
+        child: SizedBox.square(
+          dimension: widget.size,
+          child: Stack(alignment: Alignment.center, children: <Widget>[
+            Container(
+              decoration: BoxDecoration(
+                shape: BoxShape.circle,
+                color: Glass.pill,
+                border: Border.all(color: active ? Glass.accent : const Color(0x4DEAF0FA), width: 1.5),
+              ),
+            ),
+            // Cross-hair: the stick's two axes.
+            Container(width: 1, height: widget.size - 28, color: Glass.hairline),
+            Container(width: widget.size - 28, height: 1, color: Glass.hairline),
+            Transform.translate(
+              offset: knob,
+              child: Container(
+                width: 34,
+                height: 34,
+                decoration: BoxDecoration(
+                  shape: BoxShape.circle,
+                  color: active ? Glass.accent : const Color(0xCC253552),
+                  border: Border.all(color: const Color(0x66FFFFFF)),
+                ),
+              ),
+            ),
+          ]),
+        ),
+      ),
+      const SizedBox(height: 2),
+      Text(widget.caption, style: HudText.label.copyWith(fontSize: 8)),
+    ]);
+  }
+}
+
+/// The rail's STICKS button: lit while the on-screen sticks fly the aircraft.
+class SticksButton extends StatelessWidget {
+  const SticksButton({super.key, required this.open, required this.onTap});
+
+  final bool open;
+  final VoidCallback onTap;
+
+  @override
+  Widget build(BuildContext context) {
+    return GlassPill(
+      key: const ValueKey<String>('rail-sticks'),
+      height: 24,
+      color: open ? Glass.accent : Glass.pillStrong,
+      padding: const EdgeInsets.symmetric(horizontal: 6),
+      onTap: onTap,
+      child: Text('STICKS', style: HudText.label.copyWith(fontSize: 8, color: Glass.ink, fontWeight: FontWeight.w700)),
+    );
+  }
+}