Windows CMD interprets parentheses as special syntax for command grouping.
When the project directory path contains parentheses (e.g., in username),
the batch script fails with ') was unexpected at this time.' error.

This fix stores the current directory in a variable using delayed expansion
(!CURRENT_DIR!) instead of using %CD% directly, which properly handles
paths containing parentheses and other special characters.

Fixes sbt#8644

This test verifies the fix for issue sbt#8644 by:
1. Creating a test directory with parentheses in the name
2. Running sbt.bat from that directory
3. Verifying error messages display correctly without parsing errors

The test ensures that paths containing parentheses are properly
handled using delayed expansion in the batch script.

Replace the batch file test with a proper Scala integration test
following the existing test patterns in ExtendedRunnerTest.scala.

The test verifies that sbt.bat correctly handles paths containing
parentheses by:
1. Creating a temporary directory with parentheses in the name
2. Running sbt from that directory and verifying it works
3. Testing error messages display correctly without parsing errors

This addresses the reviewer's request to use Scala tests instead
of batch file tests.

Fixes sbt#8644

Use ProcessLogger to capture stderr when sbt exits with non-zero
code, instead of using !! which throws an exception on failure.

This allows the test to verify that error messages don't contain
parsing errors when paths have parentheses.

Refactor test to use IO.withTemporaryDirectory loan pattern instead
of manually creating and deleting the directory. This ensures automatic
cleanup even if an exception is thrown during test execution.