TFIL: remove the virtual centre pillar from the shipped default; register j102 env reads

The default mover painted a 30/10 radiance blob on the arena centre even
though the arena has NO physical pillar there, creating a 4x4 tile
(144x144 px) exclusion zone over open centre floor. Set
PillarHotness/PillarRadiance to 0/0 in the shipped default (matching the
ring variant) and add TR_TFIL_PILLAR_ON=1 to restore the old 30/10 field
for A/B without a rebuild; registered in env_report.

Because the shipped default legitimately changed, the default-path parity
golden (fixtures/tfil_commit_default.golden) was regenerated from the NEW
default, with an explicit 'deliberate default change' note in the test so
a future failure is treated as a real regression.

Also register the three env reads job j102 added in common_libs/bitbrain
(TR_BITBRAIN_MODE / _DECAY_EVERY / _DECAY_SHIFT), which the env-report
guard was failing on.

Verification: test_env_report all green; test_tfil_commit_env 30/30.

common_libs/movements/the_floor_is_lava.nim

@@ -31,8 +31,17 @@ const CorridorHeat = 20.0
 const WallHotness  = 30.0
 const WallRadiance = 10.0
 
-const PillarHotness  = 30.0
-const PillarRadiance = 10.0
+## The "virtual centre pillar": heat OUR code paints on the arena centre even
+## though the arena has NO physical pillar there. The shipped default is now
+## OFF (0/0) — the bot must not avoid open centre floor for no reason. Set
+## `TR_TFIL_PILLAR_ON=1` to restore the old 30/10 field for A/B (see
+## `loadTfilPillarEnv`). The ring variant already ships 0/0.
+const
+  PillarHotnessOn  = 30.0
+  PillarRadianceOn = 10.0
+var
+  PillarHotness*  = 0.0
+  PillarRadiance* = 0.0
 
 const CommitTicks           = 15    ## ticks to commit to a dodge point
 const MinCommitTicks        = 5     ## must commit for this many ticks before danger replan allowed
@@ -113,6 +122,19 @@ proc loadTfilCommitEnv*() =
 
 loadTfilCommitEnv()
 
+proc loadTfilPillarEnv*() =
+  ## Read the virtual-centre-pillar knob. OFF by default: the shipped field is
+  ## the arena with no invented centre hazard. `TR_TFIL_PILLAR_ON=1` restores
+  ## the pre-change 30/10 field so the two defaults can be A/B-ed offline.
+  if getEnvBool("TR_TFIL_PILLAR_ON", false):
+    PillarHotness  = PillarHotnessOn
+    PillarRadiance = PillarRadianceOn
+  else:
+    PillarHotness  = 0.0
+    PillarRadiance = 0.0
+
+loadTfilPillarEnv()
+
 # ── Time-indexed bullet heat (TR_TFIL_HEAT_TIME=1, default OFF = shipped) ─────
 #
 # WHY: the flat model gives every bullet-overlapping tile the same heat and