Fix Windows separator mismatch in SlotLockTest

testLogicalLockReportsLockDirectoryCreationFailure built the lock
directory path with Paths.get(parentDir, ".slot-locks"), which yields a
backslash separator on Windows. SlotLock.acquireLogical builds it as
parentDir + "/" + ".slot-locks" (forward slash), so the injected
LockDirectoryFailureFacade -- which fails mkdir only when
lockDir.equals(path) -- never matched the production path on Windows.
The mkdir then succeeded, acquireLogical did not throw, and the test hit
its fail() guard. It passed on Linux and macOS only because Paths.get
uses a forward slash there.

Build the test's lock-dir (and slot) path with the same "/"
concatenation SlotLock uses, so the facade matches on every platform.
Test-only change; no production behavior is affected.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: glasstiger

core/src/test/java/io/questdb/client/test/cutlass/qwp/client/sf/cursor/SlotLockTest.java

@@ -144,8 +144,14 @@ public void testLogicalLockRejectsInvalidPaths() throws Exception {
     @Test
     public void testLogicalLockReportsLockDirectoryCreationFailure() throws Exception {
         TestUtils.assertMemoryLeak(() -> {
-            String slot = Paths.get(parentDir, "mkdir-failure").toString();
-            String lockDir = Paths.get(parentDir, ".slot-locks").toString();
+            String slot = parentDir + "/mkdir-failure";
+            // Build the lock-dir path exactly as SlotLock.acquireLogical does
+            // (parent + "/" + ".slot-locks"), NOT via Paths.get: on Windows
+            // Paths.get yields a '\' separator, so the facade's lockDir.equals(path)
+            // check never matched the production forward-slash path and the mkdir
+            // failure was never injected -- the sole cause of the Windows-only
+            // failure of this test.
+            String lockDir = parentDir + "/.slot-locks";
             LockDirectoryFailureFacade ff = new LockDirectoryFailureFacade(lockDir);
             try {
                 SlotLock.acquireLogical(ff, slot);