[2.x] feat: sbtw launcher (#8742)

- Add sbtwProj: Scala 3.x launcher with scopt, drop-in for sbt.bat
- Config: .sbtopts, .jvmopts, sbtconfig.txt, JAVA_OPTS/SBT_OPTS precedence
- Options: --client, --server, --jvm-client, mem, sbt-version, java-home, etc.
- sbt 2.x defaults to native client; --server forces JVM launcher
- JVM run via xsbt.boot.Boot; native via sbtn with --sbt-script
- build.sbt: sbtwProj in root build and allProjects; NativeImagePlugin
- Fixes: JAVA_OPTS then .jvmopts, build.properties trim, shutdownAll PID, Iterator.lastOption

.github/workflows/client-test.yml

@@ -51,7 +51,7 @@ jobs:
       if: ${{ matrix.os == 'ubuntu-latest' }}
       shell: bash
       run: |
-        # test building sbtn on Linux
+        # test building sbtn on Linux (sbtw native-image dropped: scopt lazy vals break under Graal)
         sbt "-Dsbt.io.virtual=false" nativeImage
         # smoke test native Image
         ./client/target/bin/sbtn --sbt-script=$(pwd)/sbt about
@@ -69,7 +69,7 @@ jobs:
       if: ${{ matrix.os == 'macos-latest' }}
       shell: bash
       run: |
-        # test building sbtn on macOS
+        # test building sbtn on macOS (sbtw native-image dropped: scopt lazy vals break under Graal)
         ./sbt "-Dsbt.io.virtual=false" nativeImage
         # test launcher script
         launcher-package/bin/coursier resolve
@@ -84,19 +84,21 @@ jobs:
         max_attempts: 3
         shell: bash
         command: |
-          # test building sbtn on Windows
+          # test building sbtn on Windows (sbtw native-image dropped: scopt lazy vals break under Graal)
           sbt "-Dsbt.io.virtual=false" nativeImage
     - name: Client test (Windows)
       if: ${{ matrix.os == 'windows-latest' }}
       shell: bash
       run: |
-        # smoke test native Image
+        # smoke test native Image (sbtn)
         ./client/target/bin/sbtn --sbt-script=$(pwd)/launcher-package/src/universal/bin/sbt.bat about
         ./client/target/bin/sbtn --sbt-script=$(pwd)/launcher-package/src/universal/bin/sbt.bat shutdown
         # test launcher script
         echo build using JDK 17 test using JDK 17 and JDK 25
         launcher-package/bin/coursier.bat resolve
         sbt -Dsbt.build.version=$TEST_SBT_VER launcherPackageIntegrationTest/test
+        # integration tests with sbtw as drop-in for sbt.bat (JVM runner)
+        sbt -Dsbt.build.version=$TEST_SBT_VER -Dsbt.test.useSbtw=true launcherPackageIntegrationTest/test
         cd launcher-package/citest
         ./test.bat
         test3/test3.bat