pack: v0.29.0 — train fuel requirement + CBC tier-preserving safety

Two related gameplay tweaks:

1. Train fuel requirement (Steam 'n' Rails)
   - Set realisticTrains = true in railways-server.toml.
     Trains now consume fuel from a Fuel Tank (liquid) or solid fuels
     in chests/barrels on the contraption. realisticFuelTanks stays
     true so tanks won't accept water/junk.
   - Ship a datapack bns-fuel/ that defines TFMG fluids as proper
     liquid fuels at tiered burn rates:
       crude_oil    8000 ticks/bucket   (raw, abundant -- entry)
       furnace_gas 12000 ticks/bucket   (cheap by-product)
       naphtha     24000 ticks/bucket   (mid refined)
       kerosene    24000 ticks/bucket   (mid refined)
       gasoline    36000 ticks/bucket   (top refined)
       diesel      48000 ticks/bucket   (top refined, longest)
     Vanilla lava bucket still works via bucket-burn fallback
     (20000 ticks). Tier curve incentivises building a real refinery.

2. CBC tier-preserving cannon safety
   - Revert the nuclear disableAllCannonFailure=true switch shipped
     in v0.28 hotfix -- it killed the bronze/steel/nethersteel tier
     balance because overloaded cannons fired without consequence.
   - Per-lever config that protects against random RNG losses while
     keeping the tier mechanic intact:
       disableAllCannonFailure = false
       squibChance = 0.0              (no random projectile-stuck)
       barrelChargeBurstChance = 0.0  (forgive misplaced charges)
       interruptedIgnitionChance = 0.0 (forgive gapped loads)
       overloadBurstChance = 1.0      (TIER STRICT -- exceed your
                                       cannon's rated propellant
                                       stress = lose the cannon)
       failureExplosionPower = 0.0    (no collateral blast when it
                                       does die from overload)
   - Effect: a cannon built to spec and used within its
     maxSafePropellantStress is immortal. Overloading dies cleanly
     per the material's failureMode, no fortress damage. User error
     (squib/misplace/gap) doesn't destroy expensive builds.

Stress units NOT supported for trains: verified by inspecting Rails
and Create bytecode, nothing consumes SU for train movement. Liquid
fuel is the supported mechanism.

Verified live: server boots clean, port 25565 binds, KubeJS loads
0 errors, Minecraft auto-enables the bns-fuel datapack, Rails
initializes the LiquidFuelManager reload listener.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

pack/overrides/world/datapacks/bns-fuel/pack.mcmeta

@@ -0,0 +1,6 @@
+{
+  "pack": {
+    "pack_format": 48,
+    "description": "Brass and Sigil — Steam'n'Rails liquid fuel definitions"
+  }
+}