fix(SNNBot): binary-native input encoding with ~13 active bits

Float population code produced 0-1 active bits after binarization —
not enough to discriminate 72 bins. Replace with direct binary encoding:
5 bits per angular channel (center ± 2 neighbors), 3 bits for speed.
Adjacent bearings share 4/5 bits (smooth); distant bearings share 0
(clean separation). Fix circular error display.

SNNBot_garage/src/SNNBot.nim

@@ -380,12 +380,38 @@ method onGameStarted*(bot: SNNBot, e: GameStartedEventForBot) =
 
 # ── Reservoir helpers ─────────────────────────────────────────────────────────
 
-proc toBitVec80(inputs: array[N_IN, float]): BitVec80 =
+proc toBinaryInput(bearing: float, velDir: float, velSpeed: float, hasVel: bool): BitVec80 =
+  ## Binary-native encoding: ~5 bits per channel, ~13 total active bits
   result = [0'u64, 0'u64]
-  for i in 0 ..< N_IN:
-    if inputs[i] > 0.5:
-      let word = i div 64
-      let bit  = i mod 64
+
+  # Bearing: bits 0-35 (36 bits, 10° bands)
+  # Activate center band + 2 neighbors on each side = 5 bits
+  let bNorm = (bearing + 180.0) / 10.0  # 0..36
+  let bCenter = int(bNorm) mod 36
+  for offset in -2 .. 2:
+    let idx = (bCenter + offset + 36) mod 36
+    let word = idx div 64
+    let bit = idx mod 64
+    result[word] = result[word] or (1'u64 shl bit)
+
+  if hasVel:
+    # Velocity direction: bits 36-71 (36 bits, 10° bands)
+    # Same scheme: 5 bits active
+    let vNorm = (velDir + 180.0) / 10.0
+    let vCenter = int(vNorm) mod 36
+    for offset in -2 .. 2:
+      let idx = 36 + (vCenter + offset + 36) mod 36
+      let word = idx div 64
+      let bit = idx mod 64
+      result[word] = result[word] or (1'u64 shl bit)
+
+    # Speed: bits 72-79 (8 bits, 1 unit/tick bands)
+    # Activate center + 1 neighbor on each side = 3 bits
+    let sCenter = clamp(int(velSpeed), 0, 7)
+    for offset in -1 .. 1:
+      let idx = 72 + clamp(sCenter + offset, 0, 7)
+      let word = idx div 64
+      let bit = idx mod 64
       result[word] = result[word] or (1'u64 shl bit)
 
 # ── Main loop ─────────────────────────────────────────────────────────────────
@@ -409,9 +435,8 @@ method run*(bot: SNNBot) =
     of DECIDE:
       let relBearing = normalizeRelativeAngle(bot.enemyBearing - gunDir)
       bot.lastRelBearing = relBearing
-      let inputs = encodeInputFull(relBearing, bot.velDirDeg, bot.velSpeed, bot.hasLastPos)
       when USE_RESERVOIR:
-        let binInput  = toBitVec80(inputs)
+        let binInput  = toBinaryInput(relBearing, bot.velDirDeg, bot.velSpeed, bot.hasLastPos)
         let winBin    = bot.res.forward(binInput)
         let aimAngle  = bot.res.interpolatedAngle(winBin)
         bot.lastBinInput     = binInput
@@ -419,6 +444,7 @@ method run*(bot: SNNBot) =
         bot.lastDecideGunDir = gunDir
         echo "RES tick=" & $bot.tick & " bin=" & $winBin & " aim=" & formatFloat(aimAngle, ffDecimal, 1)
       else:
+        let inputs = encodeInputFull(relBearing, bot.velDirDeg, bot.velSpeed, bot.hasLastPos)
         # Multi-tick inference: accumulate sin/cos and spike counts over N_INFER ticks
         var totalSin = 0.0; var totalCos = 0.0
         var tickSpikes: array[N_HID, float]
@@ -477,7 +503,7 @@ method run*(bot: SNNBot) =
           echo "RES tick=" & $bot.tick & " bin=" & $winBin &
                " aim=" & formatFloat(aimAngle, ffDecimal, 1) &
                " target=" & formatFloat(targetRel, ffDecimal, 1) &
-               " err=" & formatFloat(abs(aimAngle - targetRel), ffDecimal, 1) &
+               " err=" & formatFloat(abs(normalizeRelativeAngle(aimAngle - targetRel)), ffDecimal, 1) &
                " readout_pop_correct=" & $readoutPopCorrect
         else:
           let err = abs(normalizeRelativeAngle(gunDir - bot.enemyBearing))