fix(config): deduplicate paths in config file detection

Description

• fix(config): deduplicate paths in config file detection

Fixes a bug where the same config file path could appear multiple times in the duplicate config warning when the legacy path (~/.config/glab-cli) is also in the XDG ConfigDirs list.

The checkForDuplicateConfigs() function now tracks which paths have already been seen using a seenPaths map, ensuring each unique path is only added once to the list of existing configs.

Related Issues

Resolves #[issue_number]

How has this been tested?

Screenshots (if appropriate):

Bug: