perf(hud): stop flight instruments redrawing when values have settled

hud_gauge, hud_attitude_indicator, and hud_heading_tape now skip
queue_redraw() when the newly-lerped value hasn't moved past a small
epsilon, instead of redrawing every frame forever. Angle-wrapping
values (heading, attitude roll) use a new shared angle_delta_deg
helper on HudInstrument so the wrap boundary doesn't read as a false
jump.

HUD.tscn's Instruments node now sets process_mode = 1 (PAUSABLE),
overriding the inherited ALWAYS mode from the HUD root so instruments
stop processing during the post-match pause freeze, while sibling
ResultOverlay keeps running its win-screen tween.

Game/scripts/hud_heading_tape.gd

@@ -26,10 +26,16 @@ func set_heading(heading_deg: float) -> void:
 	_target_heading = heading_deg
 
 
+# Below this, the tape has visually settled — skip the redraw.
+const REDRAW_EPSILON_DEG := 0.05
+
 func _process(delta: float) -> void:
 	var t := _smoothing_weight(delta)
-	_heading = fmod(lerp_angle_deg(_heading, _target_heading, t) + 360.0, 360.0)
-	queue_redraw()
+	var new_heading := fmod(lerp_angle_deg(_heading, _target_heading, t) + 360.0, 360.0)
+	var changed := absf(angle_delta_deg(_heading, new_heading)) > REDRAW_EPSILON_DEG
+	_heading = new_heading
+	if changed:
+		queue_redraw()
 
 
 func _draw() -> void: