- Add CombatSystem: owns the hostile pack, tracers, player armor/energy,
auto-fire (nearest-in-range), swept-hit collisions, rams, respawn — all
driven by data/combat.json `game.*` / `energy` sections
- Add CombatBar (Diablo 4 style): vertical shields + hull gauges on the
left, energy gauge on the right, eight skill seats (keys 1–8) in the
middle; shown in place of the action deck while combat is live
- `?combat` now boots the normal game with the pack spawning when the
player starts (mouse steers, cannon auto-fires); the standalone WASD
range remains at `/combat` / `combat.html`
- GameScene wires the system into its update loop, solid constraints, and
click-through gate; exposes `window.__ORBIT_COMBAT__` for DevTools
- Extend combat tests to cover CombatSystem lifecycle (spawn, auto-fire,
hits, rams, armor, respawn, cast stub, destroy)
