Introduces VegaCombatSim, a standalone dev tool for tuning and
testing VegaCombat. It allows configuring attacker/defender fleets
(or fleet vs planet), watching animated battles on the real tactical
screen, and running batch trials for win-rate statistics. Both paths
use the exact same VegaCombat stepper as the live game.
Also fixes a transport unit amount default (1 → 0) in
VegaColonyView and corrects a music file reference in the JSON
data file.
