Switch the root build scripts to Kotlin and limit parallel remaps

- settings.gradle, stonecutter.gradle and the root build.gradle become
  .kts. Loom's version for the Stonecutter versions moves to the root
  gradle.properties (loom_version), read by pluginManagement, since the
  Kotlin plugins block can't read properties. The old mc-<v> projects keep
  their Groovy scripts until they're folded in.
- buildAll ran all eight remapJar tasks at once. Each loads a Minecraft
  classpath and remaps a ~50 MB jar, which doesn't fit in the 3 GB daemon
  heap: a cold build stalled in garbage collection for 40+ minutes, and
  earlier runs failed. A shared build service now lets two remaps run
  together; a cold buildAll takes about 2 minutes.
- port.sh and VERSION_GUIDE follow the .kts file names.

The 1.21.11 jar is the same as with the Groovy scripts.

Co-Authored-By: Claude Opus 5.5 <[email protected]>

scripts/port.sh

@@ -6,9 +6,9 @@
 # normal merge conflicts only where a version really differs. Only source is
 # ported; build.gradle and gradle.properties are version-specific on purpose.
 #
-# Versions moved to Stonecutter (stonecutterVersions in settings.gradle) share
-# the top-level src/, which counts as one version: the active one set in
-# stonecutter.gradle. The others keep their own copy in versions/<v>/src.
+# Versions moved to Stonecutter (stonecutterVersions in settings.gradle.kts)
+# share the top-level src/, which counts as one version: the active one set in
+# stonecutter.gradle.kts. The others keep their own copy in versions/<v>/src.
 #
 # Usage:
 #   scripts/port.sh [--from VERSION] [--to V1,V2,...] [--commit REV] [--dry-run]
@@ -43,8 +43,8 @@ while [ $# -gt 0 ]; do
 done
 
 # Versions sharing the Stonecutter src/, and the one that stands for them.
-stonecutter_versions=$(sed -n 's/^def stonecutterVersions = \[\(.*\)\]/\1/p' settings.gradle | tr -d '" ' | tr ',' ' ')
-stonecutter_active=$(sed -n 's/^stonecutter\.active "\(.*\)"/\1/p' stonecutter.gradle 2>/dev/null || true)
+stonecutter_versions=$(sed -n 's/^val stonecutterVersions = listOf(\(.*\))/\1/p' settings.gradle.kts | tr -d '" ' | tr ',' ' ')
+stonecutter_active=$(sed -n 's/^stonecutter active "\(.*\)"/\1/p' stonecutter.gradle.kts 2>/dev/null || true)
 
 is_stonecutter() {
     printf '%s\n' $stonecutter_versions | grep -qx "$1"