diag(SNNBot): revert to baseline, add bias diagnostics

Reverted fire gate from 1° back to 2°, removed gridHasData cold-start
guard so bot fires on straight aim during cold-start. Added
/tmp/snnbot_bias_debug.log BIAS entries in EVALUATE phase logging
gridOffset, correctOffset, bias, vPerp, dist per cycle.

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

SNNBot_garage/tests/test_bullet_economy.nim

@@ -31,7 +31,7 @@ const
 
 let wallsbotDir = sampleBotsDir / "Walls"
 
-const ROUNDS = 20
+const ROUNDS = 50
 
 let r = runBattle(@[snnbotDir, wallsbotDir], rounds = ROUNDS)