chore: rename libs→common_libs, all bot dirs to _garage suffix, fix all path refs

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

tools/training_runner/curriculum_retrain.sh

@@ -5,7 +5,7 @@ set -uo pipefail
 
 SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
 REPO_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
-PPO_BOT_SRC="$REPO_ROOT/PPO_Bot"
+PPO_BOT_SRC="$REPO_ROOT/PPO_Bot_garage"
 
 # Source hyperparams (but we'll override opponent/rounds/log per phase)
 ENV_FILE="$SCRIPT_DIR/training.env"