fix: Store absolute path in attemptedPaths for accurate error reporting

Fixed Issue #9: Error message was checking file existence against CWD instead of actual resolved path.

Before:
- attemptedPaths stored raw relative path: ../parent/pom.xml
- Error check: new File(../parent/pom.xml).exists() → checked CWD (wrong!)

After:
- attemptedPaths stores absolute resolved path: /project/parent/pom.xml
- Error check: new File(/project/parent/pom.xml).exists() → correct location

This ensures error messages accurately report whether the file exists at the actual location resolution attempted, not a coincidental match in CWD.

Author: adesjardin

mule-linter-spi/src/main/groovy/com/avioconsulting/mule/linter/resolver/ParentPomResolver.groovy

@@ -91,7 +91,7 @@ class ParentPomResolver {
         // 1. Try relative path first if provided
         if (relativePath) {
             File relativePom = resolveRelativePath(relativePath, childDir)
-            attemptedPaths << relativePath
+            attemptedPaths << relativePom.absolutePath  // Store absolute path for accurate error reporting
 
             if (relativePom?.exists()) {
                 // Install to local repo for caching