j142 retire the ADE+SBC gun (rack id 17): the owner watched it, it does not learn, throw it away

Remove guns/bitbrain_net.nim (+README), test_bitbrain_net.nim,
measure_bitbrain_scaling.nim, rack id 17 and all of its plumbing in
selector.nim / ModularBot.nim / env_report.nim, the TR_BITBRAIN_NET switch
and the NEW-NETWORK TR_BITBRAIN_* knobs, and the BitBrainNet arm of
run_prediction_quality.nim.

With id 17 gone there is nothing to disambiguate, so the legacy namespace
becomes the ONLY one: TR_RACK_BITBRAIN always selects id 16 LEADGAIN and
every TR_BITBRAIN_<X> in the frozen 14-suffix alias set always means
TR_LEADGAIN_<X>. The alias layer and its [depr] line stay.

KEPT: the common_libs/bitbrain/ SBC library (learned_surfer imports
bitbrain/sbc), lead_gain at id 16 with env TR_LEADGAIN_* and log tag [lg],
and the c9b6753 crash fix (NumRackGuns widths + test_rack_stat_width).

Tombstone: docs/bitbrain_campaign.md ## RETIRED and one cross-reference line
in docs/gun_campaign.md. Shipped defaults unchanged: clean env -> rack
active 1v1 = PATTERN, movement default strafe.

ModularBot_garage/src/env_report.nim

@@ -32,7 +32,6 @@ import movements/wave_surfer
 import movements/learned_surfer
 import guns/tm_horizon
 import guns/lead_gain
-import guns/bitbrain_net
 import guns/pattern_matcher
 import vbullet_draw
 import geo_overlay
@@ -66,7 +65,6 @@ type
     disabledGuns*:     HashSet[int]
     tmHorizon*:        TmHorizonGun
     leadGain*:        LeadGainGun
-    bitbrainNet*:     BitbrainNetGun
     patternMatcher*:   PatternMatcherGun
 
 # ── helpers ──────────────────────────────────────────────────────────────────
@@ -117,8 +115,8 @@ proc sourceOfPresence(name: string): string =
 
 proc legacyNameFor(name: string): string =
   ## The legacy `TR_BITBRAIN_<X>` alias for a `TR_LEADGAIN_<X>` knob, or "" when
-  ## the knob has no legacy name / the namespace now belongs to the new gun.
-  if netSwitchOwnsBitbrainName(): return ""
+  ## the knob has no legacy name. This gun is the sole owner of the
+  ## `TR_BITBRAIN_*` prefix (the ADE+SBC gun that briefly shared it was retired).
   if not name.startsWith(NewPrefix): return ""
   let suffix = name[NewPrefix.len .. ^1]
   for s in LegacyKnobEnvNames:
@@ -141,9 +139,6 @@ proc sourceOfLgPresence(name: string): string =
   else:
     sourceOfPresence(name)
 
-proc sbcModeName(m: SbcMode): string {.inline.} =
-  (if m == smCounted: "counted" else: "bitset")
-
 proc disabledGunsString(guns: HashSet[int]): string =
   if guns.len == 0: return "none"
   var ids: seq[int]
@@ -425,40 +420,12 @@ proc printEffectiveValues(ctx: EnvReportContext) =
   emit("TR_LEADGAIN_SEED", $lg.seed, sourceOfLg(LG_SEED_ENV))
   emit("TR_LEADGAIN_RESET_ON_TARGET", onOff(lg.resetOnTarget),
        sourceOfLg(LG_RESET_ON_TARGET_ENV))
-  # The disambiguation switch + the deprecation line it gates, in the report so
-  # an owner staring at a `[depr]` line can see exactly why it fired.
-  emit("TR_BITBRAIN_NET", onOff(netSwitchOwnsBitbrainName()),
-       sourceOfPresence("TR_BITBRAIN_NET"))
+  # The deprecation line the legacy alias layer can print, in the report so an
+  # owner staring at a `[depr]` line can see exactly which knob fired.
   let dep = lgDeprecationLine()
   if dep.len > 0: emit("legacy TR_BITBRAIN_* aliases honoured", "yes", "legacy")
   else: emit("legacy TR_BITBRAIN_* aliases honoured", "no", "default")
 
-  # ── the ADE+SBC gun (rack id 17) ─────────────────────────────────────────
-  # Two switches admit it, both default off: `TR_RACK_BITBRAIN` (rack table) and
-  # `TR_BITBRAIN_NET` (the gun's own master switch, which is also the switch
-  # that disowns the legacy `TR_BITBRAIN_*` aliases above).
-  let bbn = ctx.bitbrainNet
-  emit("TR_BITBRAIN_NET", onOff(bbn.enabled), sourceOfPresence(BBN_NET_ENV))
-  emit("TR_BITBRAIN_INPUT", $bbn.inputWidth, sourceOf(BBN_INPUT_ENV))
-  emit("TR_BITBRAIN_FEATURES", bbn.features, sourceOf(BBN_FEATURES_ENV))
-  emit("TR_BITBRAIN_NCLASSES", $bbn.nClasses, sourceOf(BBN_CLASSES_ENV))
-  emit("TR_BITBRAIN_NADES", $bbn.nAde, sourceOf(BBN_NADES_ENV))
-  emit("TR_BITBRAIN_WIDTHS", bbn.widths.join(","), sourceOf(BBN_WIDTHS_ENV))
-  emit("TR_BITBRAIN_SPAN", $bbn.maxDeg, sourceOf(BBN_SPAN_ENV))
-  emit("TR_BITBRAIN_MODE", sbcModeName(bbn.mode), sourceOf(BBN_MODE_ENV))
-  emit("TR_BITBRAIN_DECAY_EVERY", $bbn.decayEvery, sourceOf(BBN_DECAY_EVERY_ENV))
-  emit("TR_BITBRAIN_DECAY_SHIFT", $bbn.decayShift, sourceOf(BBN_DECAY_SHIFT_ENV))
-  emit("TR_BITBRAIN_MINOBS", $bbn.minObs, sourceOf(BBN_MINOBS_ENV))
-  emit("TR_BITBRAIN_ADAPT_EVERY", $bbn.adaptEvery, sourceOf(BBN_ADAPT_ENV))
-  emit("TR_BITBRAIN_TARGET", $bbn.targetRate, sourceOf(BBN_TARGET_ENV))
-  emit("TR_BITBRAIN_NETSEED", $bbn.seed, sourceOf(BBN_SEED_ENV))
-  emit("TR_BITBRAIN_NETLOG", onOff(bbn.logEnabled),
-       sourceOfPresence(BBN_LOG_ENV))
-  emit("bitbrain_net.ram", $bbn.networkBytes, "default")   ## 0 until the lazy build
-  emit("bitbrain_net.admitted", onOff(bbn.gunAdmitted(
-         ActiveRackMembership[17] != rmOff)),
-       "default")  ## rack table AND TR_BITBRAIN_NET; both default off
-
   # ── Pattern match-shape + 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.
@@ -514,7 +481,7 @@ proc printModules(ctx: EnvReportContext) =
   # mode = enabled in that rack.
   for i in 0..<len(RackGunNames):
     var src = sourceOf(RackEnvPrefix & RackGunNames[i])
-    if src == "default" and not netSwitchOwnsBitbrainName():
+    if src == "default":
       for (key, gid) in RackLegacyAlias:
         if gid == i and getEnv(key, "").len > 0:
           src = if isFromEnvFile(key): "legacy/.env" else: "legacy"
@@ -621,26 +588,28 @@ proc knownEnvNames*(): seq[string] =
     TMH_RETRAIN_EVERY_ENV, TMH_EPOCHS_ENV,
     LG_MEM_ENV, LG_GAINS_ENV, LG_N_ENV, LG_NADE_ENV, LG_RANGE_ENV, LG_LOG_ENV,
     LG_MIN_OBS_ENV, LG_WARMUP_ENV, LG_ADAPT_ENV, LG_CALIB_ENV, LG_DECAY_ENV,
-    LG_DECAY_FRAC_ENV, LG_SEED_ENV, LG_RESET_ON_TARGET_ENV, LG_NET_SWITCH_ENV,
-    # LEGACY aliases of the corrector knobs above (honoured while
-    # LG_NET_SWITCH_ENV is off). Registered so the tree-scan guard does not
-    # flag the owner's pre-rename .env as unknown.
+    LG_DECAY_FRAC_ENV, LG_SEED_ENV, LG_RESET_ON_TARGET_ENV,
+    # LEGACY aliases of the corrector knobs above, honoured UNCONDITIONALLY
+    # (this gun is the sole owner of the `TR_BITBRAIN_*` prefix). Registered so
+    # the tree-scan guard does not flag the owner's pre-rename .env as unknown.
     "TR_BITBRAIN_GAINS", "TR_BITBRAIN_MEM", "TR_BITBRAIN_MIN_OBS",
     "TR_BITBRAIN_DECAY", "TR_BITBRAIN_DECAY_FRAC", "TR_BITBRAIN_LOG",
     "TR_BITBRAIN_RESET_ON_TARGET", "TR_BITBRAIN_N", "TR_BITBRAIN_NADE",
     "TR_BITBRAIN_RANGE", "TR_BITBRAIN_WARMUP", "TR_BITBRAIN_ADAPT",
     "TR_BITBRAIN_CALIB", "TR_BITBRAIN_SEED",
-    # common_libs/bitbrain (counted-SBC library) reads these inline; job j102
+    # common_libs/bitbrain (the SBC LIBRARY, which STAYS — `learned_surfer`
+    # imports bitbrain/sbc) reads these three inline; they are the library's own
+    # knobs, not the retired ADE+SBC gun's (that gun, rack id 17, was removed).
+    "TR_BITBRAIN_MODE", "TR_BITBRAIN_DECAY_EVERY", "TR_BITBRAIN_DECAY_SHIFT",
   ]
-  # the ADE+SBC gun (rack id 17) owns the rest of the TR_BITBRAIN_* namespace
-  for n in BitbrainNetEnvNames: result.add n
   # rack names are constructed from the prefix + gun table, not spelled out
   for g in RackGunNames:
     result.add RackEnvPrefix & g
-  # NOTE: the legacy rack alias `TR_RACK_BITBRAIN` needs no extra entry — it is
-  # the CURRENT name of rack id 17, so the RackGunNames loop above already
-  # registers it. See gun_harness/selector's RackLegacyAlias for how it is
-  # routed to LEADGAIN while LG_NET_SWITCH_ENV is off.
+  # the legacy rack alias `TR_RACK_BITBRAIN` is no longer in `RackGunNames`
+  # (it is LEADGAIN's old name), so register it explicitly. See
+  # gun_harness/selector's RackLegacyAlias.
+  for (key, _) in RackLegacyAlias:
+    result.add key
   # inline reads with no exported constant (the guard test scans for these)
   for n in [
     "GUN_SELECTOR_WINDOW", "GUN_SELECTOR_MINOBS", "GUN_SELECTOR_TIE",