docs: record java toolchain requirement and refresh counts

JAVA_MIGRATION_HANDOFF.md

@@ -17,8 +17,8 @@ migration checkout; `codex/tile-compatibility-fixes` was deleted after its fixes
 
 ## Current state and next target
 
-**573 plain-JVM tests and 289 Java 8 Forge tests pass, with zero failures/errors/skips.** Sources total **225 Java
-files and 9 Scala files / 747 nonblank Scala lines**. The packaged inventory has 444 classes.
+**576 plain-JVM tests and 289 Java 8 Forge tests pass, with zero failures/errors/skips.** Sources total **230 Java
+files and 9 Scala files / 747 nonblank Scala lines**. The packaged inventory has 450 classes.
 
 Review follow-up: restored packet-scheduler callback mutation behavior with the original Scala hash-map traversal,
 virtual tile accessor dispatch throughout `TMultiPart`, and null-safe equality for scheduled-tick deduplication.

README.md

@@ -6,7 +6,11 @@ An API for dynamically handling different functional parts in the one block spac
 Requirements:
 * The latest version of CCL (files.minecraftforge.net/CodeChickenLib/)
 * Forge
-* A scala compatible IDE and project (For eclipse, download the scala eclipse plugin and right click on the project -> Add Scala Nature)
+* JDK 8 and JDK 25. The mod targets Java 8, but a small set of helpers is compiled at Java 21 by the
+  `compileModernJava` task and downgraded to Java 8, so both toolchains must be resolvable to build.
+* A scala compatible IDE and project (For eclipse, download the scala eclipse plugin and right click on the project -> Add Scala Nature).
+  Most of the codebase is Java now; the Java sources live under `src/main/scala` so they can be joint-compiled
+  with the Scala files that remain.
 
 If you only want to use the API and not modify it:
  * Download the latest dev version from files.minecraftforge.net/ForgeMultipart/