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_instrument.gd

@@ -13,5 +13,13 @@ static func lerp_angle_deg(from: float, to: float, weight: float) -> float:
 	return rad_to_deg(lerp_angle(deg_to_rad(from), deg_to_rad(to), weight))
 
 
+# Shortest signed distance from `from` to `to` in degrees, wrapped to
+# [-180, 180]. Use this (never a plain subtraction) to decide whether an
+# angle that wraps around (heading, roll) has moved enough to redraw —
+# a naive delta gives a false-large jump at the 0/360 boundary.
+static func angle_delta_deg(from: float, to: float) -> float:
+	return wrapf(to - from, -180.0, 180.0)
+
+
 func _smoothing_weight(delta: float) -> float:
 	return 1.0 - exp(-SMOOTHING * delta)  # frame-rate independent