Remove Apex Dynamics faction, retune bullet speed/size

Drop Apex Dynamics from the playable roster (2 races now: Inner Sphere
Navy, Outer Rim Collective) to simplify the 2D art pipeline; World's
race-offer logic just shuffles both remaining races instead of picking
2 of N. Also fix bullets using a constant muzzle velocity instead of
adding the shooter's own velocity, and shrink the bullet hitbox/sprite.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

overview/bots.md

@@ -2,7 +2,7 @@
 
 ## Rules
 
-- Each casual match picks **2 of the 3 races** at random
+- Each casual match fields both races (order presented is randomized)
 - Bots fill empty slots until the match reaches **7v7** (14 total)
 - Once 7v7 is reached, **no more bots are added** — additional human players replace bots as they join
 - Bots are removed when real players join their team slot