port to Minecraft 26.3

Source changes for 26.3 API breakage:
- block codec system removed upstream (Block has no MapCodec/codec()/
  simpleCodec anymore): drop CODEC + codec() from AmethystCauldronBlock
  and GravityCrystalBlock
- Entity.hurtMarked -> Entity.syncVelocity (pure rename, still public)
- LivingEntity.drop() now takes a Prediction; our drops are server-
  initiated and unpredicted, so they pass SERVER_ONLY
- canSimulateMovement() became final; the ravager/hoglin mount mixins
  now override getMoveSimulationType() and return
  AUTHORITATIVE_SIDE_AND_SERVER, which is the same "server always
  simulates" semantics the old !isClientSide branch had
- loot number providers split into providers.number.{ints,floats} and
  became Holder-based: UniformGenerator.between(1f,3f) ->
  ContextIntProviders.between(1,3)
- BonemealableBlock methods take a BonemealSource (INTERACTION here)
- clockManager().getTotalTicks(c) ->
  clockManager().getInstance(c).totalTicks()
- EnderMan -> Enderman (capitalisation only)

Build: MC 26.3, loader 0.19.5, fabric-api 0.160.5+26.3, loom 1.18.1,
gradle wrapper 9.6.0 -> 9.7.1 (loom 1.18.x requires Gradle >= 9.7).
Polymer is 0.18.0+26.3-rc-1: upstream has not published a 26.3-final
build yet, that rc build is the only one on the 26.3 line.

server-deploy: pack.toml -> 26.3 / loader 0.19.5; fabric-api, polymer
and simple-voice-chat are the only pack mods with 26.3 builds and were
updated (index hashes regenerated). The remaining third-party mods have
no 26.3 release yet and are deliberately left untouched. Dockerfile now
pins the justbackup and fabric-carpet forks to their 26.3 branches
instead of silently building whatever the default branch holds.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

server-deploy/pack/index.toml

@@ -2,7 +2,7 @@ hash-format = "sha256"
 
 [[files]]
 file = "mods/fabric-api.pw.toml"
-hash = "dc5490cc1a9231b0d32ec3e72f9d34279fc1d1ff6fb5a7d288b1f36faec0a6a0"
+hash = "e3a8b560330802ec556f34a7de7a73bc712202359a657a36b39e6f85598bf8b8"
 metafile = true
 
 [[files]]
@@ -47,12 +47,12 @@ metafile = true
 
 [[files]]
 file = "mods/polymer.pw.toml"
-hash = "2a5626a6d9b61f968f294466e9756fbafa1c1208b4fb53c53cfc8d2afb42a857"
+hash = "2dec8c17d9d6fdf6dd93e2dc458c8d30ead86b2efc292490142841aacd4d3e95"
 metafile = true
 
 [[files]]
 file = "mods/simple-voice-chat.pw.toml"
-hash = "be7369da963f5326a771bbfa360365ac6ed939b01c2c268f4dd4a922718cd4a3"
+hash = "e55e25489644c7297a7f4cda6618437891fd0aba88e7f670a0439c3eadc14fc0"
 metafile = true
 
 [[files]]