Add flaps: flappable tag, flap lever on the control node, flap physics (0.4.0)

Shift-right-click a block in improved_aerodynamics:flappable to make it a flap.
G/H step the node's flap lever UP/TAKEOFF/LANDING; flaps slew to the configured
angle, add lift and drag and raise the stall angle, and retract above a max speed.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01YVREx3uo7nz1FEhzveWTUh

src/main/resources/assets/improved_aerodynamics/lang/en_us.json

@@ -22,5 +22,16 @@
   "message.improved_aerodynamics.afterburner.off": "Afterburner off",
   "message.improved_aerodynamics.afterburner.throttle": "The afterburner needs a throttle of at least %s",
   "message.improved_aerodynamics.afterburner.no_seat": "Sit in a Warium control seat to use the afterburner",
-  "message.improved_aerodynamics.afterburner.no_node": "This seat is not linked to a vehicle control node"
+  "message.improved_aerodynamics.afterburner.no_node": "This seat is not linked to a vehicle control node",
+  "key.improved_aerodynamics.flaps_down": "Flaps down (one step)",
+  "key.improved_aerodynamics.flaps_up": "Flaps up (one step)",
+  "message.improved_aerodynamics.flaps": "Flaps: %s",
+  "message.improved_aerodynamics.flaps.up": "up",
+  "message.improved_aerodynamics.flaps.takeoff": "takeoff",
+  "message.improved_aerodynamics.flaps.landing": "landing",
+  "message.improved_aerodynamics.flaps.no_seat": "Sit in a Warium control seat to use the flaps",
+  "message.improved_aerodynamics.flaps.no_node": "This seat is not linked to a vehicle control node",
+  "message.improved_aerodynamics.flap.on": "Control surface is now a flap",
+  "message.improved_aerodynamics.flap.off": "Control surface is a normal control surface again",
+  "message.improved_aerodynamics.flap.unlinked": "Control surface is now a flap, but it is not linked to a vehicle control node yet"
 }