BitBrain gun (id 16): Pattern-relative ADE+SBC aim corrector, default off

Wire the verified common_libs/bitbrain ADE+SBC library into ModularBot as a
fine-grained angular corrector on top of Pattern's prediction, the shape the
offline gate test measured (argmax readout over N correction classes).

- common_libs/guns/bitbrain_gun.nim: new gun. Input = the existing TMHorizon
  53 bits (tmhBaseBits + tmhLits); output = argmax class centre over
  +-TR_BITBRAIN_RANGE, applied by rotating the Pattern point around the shooter
  exactly as tmhApplyShift does. Label = the +h-tick fact from TmHorizonGun's
  own observation ring (never across a round). Prequential (defer + resolve).
  AD layer synthesised online for our binary inputs (center=0): heuristic
  cold-start thresholds + running-histogram ~1% percentile init + the library's
  adaptThresholds. Memory modes perRound (default, measured best) / retained /
  decay (periodic partial SBC wipe). Lazy network build + local RNG, so the
  default path builds nothing and consumes no global randomness.
- tm_horizon.nim: export tmhUpdateHistory and add tmhObservedAt (label seam).
- selector.nim: register BITBRAIN at rack id 16, default rmOff, in the SAME
  commit as the id and the wiring (the aed579b admission bug is not repeated).
- ModularBot.nim: id 16 wired through predict/spawn/onResult/resets/colors,
  arrays grown 16->17, spawn gated on rack admission, per-round/per-battle/
  target reset hooks.
- env_report.nim: report every TR_BITBRAIN_* knob + add names to the known set.
- tests: update the rack length literals; new test_bitbrain_registration
  (default-parity: off, lazy, global-RNG clean).

Guard counts unchanged: rack 48, tm_pattern_registration 20, vbullet_admit 12,
env_report 25, and the rest of the suite green.

ModularBot_garage/src/env_report.nim

@@ -26,6 +26,7 @@ import movements/ram_decision
 import movements/the_floor_is_lava
 import movements/the_floor_is_lava_ring
 import guns/tm_horizon
+import guns/bitbrain_gun
 import guns/pattern_matcher
 
 const EnvReportEnableEnvVar* = "TR_ENV_REPORT"
@@ -50,6 +51,7 @@ type
     shotLogPath*:      string
     disabledGuns*:     HashSet[int]
     tmHorizon*:        TmHorizonGun
+    bitbrain*:         BitBrainGun
     patternMatcher*:   PatternMatcherGun
 
 # ── helpers ──────────────────────────────────────────────────────────────────
@@ -281,6 +283,28 @@ proc printEffectiveValues(ctx: EnvReportContext) =
        sourceOf("TR_TMHORIZON_RETRAIN_EVERY"))
   emit("TR_TMHORIZON_EPOCHS", $tmh.retrainEpochs, sourceOf("TR_TMHORIZON_EPOCHS"))
 
+  # ── the BitBrain ADE+SBC corrector ────────────────────────────────────────
+  # All knobs are resolved at gun construction (`initBitBrainGun`), so the
+  # context holds the real values. The network itself is only built on the first
+  # `predict`, which is why `[rack]` membership is the actual enable switch.
+  emit("TR_BITBRAIN_MEM", memModeName(ctx.bitbrain.memMode),
+       sourceOf(BB_MEM_ENV))
+  emit("TR_BITBRAIN_N", $ctx.bitbrain.nClasses, sourceOf(BB_N_ENV))
+  emit("TR_BITBRAIN_NADE", $ctx.bitbrain.nAde, sourceOf(BB_NADE_ENV))
+  emit("TR_BITBRAIN_RANGE", $ctx.bitbrain.maxDeg, sourceOf(BB_RANGE_ENV))
+  emit("TR_BITBRAIN_LOG", onOff(ctx.bitbrain.logEnabled),
+       sourceOfPresence(BB_LOG_ENV))
+  emit("TR_BITBRAIN_MIN_OBS", $ctx.bitbrain.minObs, sourceOf(BB_MIN_OBS_ENV))
+  emit("TR_BITBRAIN_WARMUP", $ctx.bitbrain.warmupN, sourceOf(BB_WARMUP_ENV))
+  emit("TR_BITBRAIN_ADAPT", $ctx.bitbrain.adaptEvery, sourceOf(BB_ADAPT_ENV))
+  emit("TR_BITBRAIN_CALIB", $ctx.bitbrain.calibEvery, sourceOf(BB_CALIB_ENV))
+  emit("TR_BITBRAIN_DECAY", $ctx.bitbrain.decayEvery, sourceOf(BB_DECAY_ENV))
+  emit("TR_BITBRAIN_DECAY_FRAC", $ctx.bitbrain.decayFrac,
+       sourceOf(BB_DECAY_FRAC_ENV))
+  emit("TR_BITBRAIN_SEED", $ctx.bitbrain.seed, sourceOf(BB_SEED_ENV))
+  emit("TR_BITBRAIN_RESET_ON_TARGET", onOff(ctx.bitbrain.resetOnTarget),
+       sourceOf(BB_RESET_ON_TARGET_ENV))
+
   # ── Pattern radial knobs ──────────────────────────────────────────────────
   # These are resolved lazily inside `predict` (which has not run at boot), so
   # unless something already forced them we report the raw env value and say so.
@@ -347,6 +371,9 @@ proc knownEnvNames*(): seq[string] =
     TMH_SHIFT_ENV, TMH_BIG_MULT_ENV, TMH_LOG_ENV, TMH_RESET_ON_TARGET_ENV,
     TMH_WINDOW_ENV, TMH_RESET_DROP_ENV, TMH_NSTATES_ENV, TMH_ACCURVE_ENV,
     TMH_RETRAIN_EVERY_ENV, TMH_EPOCHS_ENV,
+    BB_MEM_ENV, BB_N_ENV, BB_NADE_ENV, BB_RANGE_ENV, BB_LOG_ENV,
+    BB_MIN_OBS_ENV, BB_WARMUP_ENV, BB_ADAPT_ENV, BB_CALIB_ENV, BB_DECAY_ENV,
+    BB_DECAY_FRAC_ENV, BB_SEED_ENV, BB_RESET_ON_TARGET_ENV,
   ]
   # rack names are constructed from the prefix + gun table, not spelled out
   for g in RackGunNames: