jackchuka/gh-oss-watch

AI Summary: Enhance the `gh oss-watch` CLI plugin's `add` command to accept repository identifiers in various formats, including URLs, Git repository URLs, and Go import paths, in addition to the current `owner/repo` format. This involves modifying the `ParseRepoString` function to handle these additional formats correctly.

AI Summary: Implement validation in the `gh-oss-watch add` command to check if the specified GitHub repository exists before adding it to the watch list. This involves making an API call to the GitHub API to verify the repository's existence and handling potential errors (e.g., 404 Not Found).