fix: flaky RenameRegex fullpath test matching GUID in temp path

The Scope_fullpath_matches_entire_path_within_directory test used "abc"
as its regex pattern. Since TempDirectory paths contain hex GUIDs, "abc"
could randomly appear in the directory portion, causing the fullpath
replacement to alter the directory and trigger PathGuard. Changed to
"klm" (non-hex chars) so it can never match the temp directory path.

Co-Authored-By: Rooty

Author: Wintersta7e

tests/FlowForge.Tests/Nodes/RenameRegexNodeTests.cs

@@ -70,14 +70,16 @@ public async Task Scope_filename_only_matches_filename_part()
     [Fact]
     public async Task Scope_fullpath_matches_entire_path_within_directory()
     {
+        // Use non-hex characters (klm) so the pattern can't accidentally match
+        // inside the hex GUID portion of the temp directory path.
         using var tempDir = new TempDirectory();
-        tempDir.CreateFiles("abc_test.txt");
+        tempDir.CreateFiles("klm_test.txt");
 
-        string filePath = Path.Combine(tempDir.Path, "abc_test.txt");
+        string filePath = Path.Combine(tempDir.Path, "klm_test.txt");
         FileJob job = MakeJob(filePath);
 
         var node = new RenameRegexNode(NullLogger<RenameRegexNode>.Instance);
-        node.Configure(MakeConfig(new { pattern = "abc", replacement = "xyz", scope = "fullpath" }));
+        node.Configure(MakeConfig(new { pattern = "klm", replacement = "xyz", scope = "fullpath" }));
 
         IEnumerable<FileJob> result = await node.TransformAsync(job, dryRun: true);