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/scenes/HUD.tscn

@@ -171,6 +171,7 @@ text = "0 - 0"
 horizontal_alignment = 1
 
 [node name="Instruments" type="Control" parent="Control"]
+process_mode = 1
 layout_mode = 1
 anchors_preset = 15
 anchor_right = 1.0