fix: Update line number retrieval in UnitTestsCVProvider

- Replace direct startOffset/endOffset with textRange.startOffset/endOffset
- Apply consistent approach for both element and element.parent
- Ensure proper line number calculation for unit test generation

Author: yangbobo2021

src/main/kotlin/ai/devchat/plugin/hints/UnitTestsCVProvider.kt

@@ -17,10 +17,10 @@ class UnitTestsCVProvider : ChatCVProviderBase() {
                 "message" to "/unit_tests " + listOf(
                     FileDocumentManager.getInstance().getFile(editor.document)!!.path,
                     (element as? PsiNamedElement)?.name,
-                    editor.document.getLineNumber(element.startOffset),
-                    editor.document.getLineNumber(element.endOffset),
-                    editor.document.getLineNumber(element.parent.startOffset),
-                    editor.document.getLineNumber(element.parent.endOffset),
+                    editor.document.getLineNumber(element.textRange.startOffset),
+                    editor.document.getLineNumber(element.textRange.endOffset),
+                    editor.document.getLineNumber(element.parent.textRange.startOffset),
+                    editor.document.getLineNumber(element.parent.textRange.endOffset),
                 ).joinToString(":::"),
             )
         )