Movement commands now access the zone through player.location instead of
a module-level world variable. send_nearby_message uses
zone.contents_near() to find nearby entities, eliminating the need for
the global players dict and manual distance calculations.
Tests updated to create zones and add entities via location assignment.
Phase 6: spawn command creates mobs at player position from loaded
templates. Server loads mob templates from content/mobs/ at startup,
injects world into combat/commands module, and runs process_mobs()
each game loop tick after process_combat().
Phase 5: process_mobs() runs each tick, handling mob attack and defense
decisions. Mobs pick random attacks from their move list when IDLE,
swap roles if needed, and attempt defense during TELEGRAPH/WINDOW with
a 40% chance of correct counter. 1-second cooldown between actions.
Training dummies with empty moves never fight back.
