fix(SNNBot): hold aim when error is within dead zone

Adds aim-lock mechanism to prevent re-running forward() pass during DECIDE when the
error is already within 1.5° dead zone. Lock is set in EVALUATE when error < 1.5°,
reusing the previous targetAngle in DECIDE. Lock releases on fresh enemy scan or when
error exceeds threshold, eliminating the ±0.9° wobble from input pattern drift.

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

SNNBot_garage/src/SNNBot.nim

@@ -215,6 +215,7 @@ type
     velSpeed:        float64            # speed (units/tick) from last scan delta
     lastDecideGunDir: float             # gun heading captured at DECIDE time for EVALUATE
     lastBinInput:    BitVec80           # DECIDE-time binary input, reused in EVALUATE
+    aimLocked:       bool               # when true, skip forward() and reuse targetAngle
 
 # ── aimTo helper ──────────────────────────────────────────────────────────────
 
@@ -254,6 +255,7 @@ method onScannedBot*(bot: SNNBot, e: ScannedBotEvent) =
   bot.enemyBearing = directionTo(bx, by, e.x, e.y)
   bot.enemyDist    = distanceTo(bx, by, e.x, e.y)
   bot.hasContact   = true
+  bot.aimLocked    = false  # release lock on fresh enemy scan
   if bot.hasLastPos:
     let dx = e.x - bot.lastEnemyX
     let dy = e.y - bot.lastEnemyY
@@ -273,6 +275,7 @@ method onRoundStarted*(bot: SNNBot, e: RoundStartedEvent) =
   bot.velSpeed     = 0.0
   bot.phase        = DECIDE
   bot.tick         = 0
+  bot.aimLocked    = false
   setTargetSpeed(0.0)
   setTurnRate(0.0)
 
@@ -335,6 +338,7 @@ method run*(bot: SNNBot) =
 
     case bot.phase
     of DECIDE:
+      if not bot.aimLocked:
         let relBearing = normalizeRelativeAngle(bot.enemyBearing - gunDir)
         bot.lastRelBearing = relBearing
         when USE_RESERVOIR:
@@ -404,18 +408,28 @@ method run*(bot: SNNBot) =
             let aimErr = abs(normalizeRelativeAngle(aimRaw - correctAngle))
             if aimErr > 1.5:
               bot.res.learn(bot.lastBinInput, correctAngle)
+              bot.aimLocked = false  # error still large, keep recomputing
+            else:
+              bot.aimLocked = true   # error within dead zone, freeze aim
           else:
             # Cold start: always learn
             bot.res.learn(bot.lastBinInput, correctAngle)
+            bot.aimLocked = false
           let aimErr = if aimRaw >= 0.0: abs(normalizeRelativeAngle(aimRaw - correctAngle)) else: -1.0
           echo "RES tick=" & $bot.tick &
                " aim=" & (if aimRaw >= 0.0: formatFloat(aimRaw, ffDecimal, 1) else: "cold") &
                " correct=" & formatFloat(correctAngle, ffDecimal, 1) &
                " err=" & (if aimRaw >= 0.0: formatFloat(aimErr, ffDecimal, 1) else: "n/a") &
-               " exemplars=" & $bot.res.count
+               " exemplars=" & $bot.res.count &
+               " lock=" & (if bot.aimLocked: "ON" else: "OFF")
         else:
           let err = abs(normalizeRelativeAngle(gunDir - bot.enemyBearing))
           bot.snn.superSpikeUpdate(bot.lastSpikes, bot.lastVSnap, bot.snn.preTrace, targetRel)
+          # Aim lock: freeze when error within 1.5° threshold
+          if err < 1.5:
+            bot.aimLocked = true
+          else:
+            bot.aimLocked = false
           # Compute verbose logging metrics
           var spikeCount = 0
           var maxV = 0.0
@@ -432,7 +446,7 @@ method run*(bot: SNNBot) =
           for w in bot.snn.wCos:
             meanWout += abs(w)
           meanWout /= float(2 * N_HID)
-          echo "tick=" & $bot.tick & " err=" & formatFloat(err, ffDecimal, 1) & "° infer_spk=" & $spikeCount & "/" & $(N_INFER * N_HID) & " maxV=" & formatFloat(maxV, ffDecimal, 3) & " |wih|=" & formatFloat(meanWih, ffDecimal, 4) & " |wOut|=" & formatFloat(meanWout, ffDecimal, 4) & " sin=" & formatFloat(bot.snn.lastSinOut, ffDecimal, 3) & " cos=" & formatFloat(bot.snn.lastCosOut, ffDecimal, 3) & " snnAngle=" & formatFloat(bot.snn.lastSnnAngle, ffDecimal, 1)
+          echo "tick=" & $bot.tick & " err=" & formatFloat(err, ffDecimal, 1) & "° infer_spk=" & $spikeCount & "/" & $(N_INFER * N_HID) & " maxV=" & formatFloat(maxV, ffDecimal, 3) & " |wih|=" & formatFloat(meanWih, ffDecimal, 4) & " |wOut|=" & formatFloat(meanWout, ffDecimal, 4) & " sin=" & formatFloat(bot.snn.lastSinOut, ffDecimal, 3) & " cos=" & formatFloat(bot.snn.lastCosOut, ffDecimal, 3) & " snnAngle=" & formatFloat(bot.snn.lastSnnAngle, ffDecimal, 1) & " lock=" & (if bot.aimLocked: "ON" else: "OFF")
       bot.phase = DECIDE
 
     # Radar lock