Updated plan §3.7.1 zone parameter table to reflect the proven
implementation in ConfigForPlayers(). The previous plan values
(ZoneStartTurn=20/15, ZoneShrinkInterval=2) did not achieve the
stated combat density targets. The current values
(ZoneStartTurn=10, ZoneShrinkInterval=1) achieve 77% combat density
for 2-player and 99% for 6-player (targets: 65-80% and 100%).
Also updated code comments in engine/types.go to remove outdated
references to the old plan values.
TestCombatDensityMetrics passes with these parameters.
Closes: bf-3og6
8cc955ba87