fix: make nested git repository warning persistent with path info

- Changed from showWarningMessage to showErrorMessage for persistence
- Modified getNestedGitRepository to return the specific path
- Updated all i18n translations to include path parameter
- Updated tests to match new error message format

Fixes #7884

Author: roomote

src/i18n/locales/ca/common.json

@@ -29,7 +29,7 @@
 		"checkpoint_timeout": "Timed out when attempting to restore checkpoint.",
 		"checkpoint_failed": "Failed to restore checkpoint.",
 		"git_not_installed": "Git is required for the checkpoints feature. Please install Git to enable checkpoints.",
-		"nested_git_repos_warning": "Checkpoints are disabled because nested git repositories were detected in the workspace. To use checkpoints, please remove or relocate nested git repositories.",
+		"nested_git_repos_warning": "Checkpoints are disabled because a nested git repository was detected at: {{path}}. To use checkpoints, please remove or relocate this nested git repository.",
 		"no_workspace": "Please open a project folder first",
 		"update_support_prompt": "Failed to update support prompt",
 		"reset_support_prompt": "Failed to reset support prompt",