3D flight simulator: 6-DOF physics, three.js r160, browser HUD

- Detailed flight dynamics: aero lift/drag/side-force with smooth stall,
  control-surface moments, stability derivatives, engine spool with prop
  torque and gyro precession, inertial coupling, ISA atmosphere, ground
  effect, 3-point gear handling, landing vs crash classification.
- Pure ESM, zero build step; three.js vendored locally. Deterministic
  simulation; physics core is Node-testable (14 node:test cases).
- Procedural 8 km world with runway, water, sky dome, cloud wrap; DOM
  instrument panel (attitude indicator, tapes, VSI, lamps, stall warning).
- Controls: WASD/arrows, Q/E rudder, Shift/Ctrl throttle, F flaps, G gear,
  B brakes, C camera (chase/cockpit/orbit), R reset, P pause, D debug.

.gitignore

@@ -0,0 +1,4 @@
+node_modules/
+.smoke*/
+*.log
+.DS_Store