chore: standardize internal bot dir structure (src/, tests/, out/)

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

PPO_Bot_garage/tests/diag_ppo_fullbuffer.nim

@@ -4,8 +4,8 @@
 
 import std/[math, random]
 import arraymancer
-import "../network"
-import "../training"
+import PPO_Bot/network
+import PPO_Bot/training
 
 var ac = initActorCritic()
 var adam: ACAdamStates  # uninitialised → ppoUpdate must reinit (fresh-process path)