Fix GitHub repository creation and clone logic in scan storage

[huseynovvusal]

Description

This PR fixes two critical failure cases in the get_or_init_repo() bootstrap flow during scan storage, which previously broke when handling existing remote repositories or correctly creating new ones.

The Issues

1. Name Mismatch: get_github_repos() was yielding full repository names (e.g., org/repo-name), which caused the simple repo_name not in get_github_repos() membership check to silently fail and incorrectly attempt to recreate existing repositories.
2. Missing Clone URLs:
   • When a new repository was created, create_github_repo() did not return the new clone URL, causing Repo.clone_from() to fail with a None URL.
   • If the repository already existed remotely, repo_url was never defined, resulting in an undefined variable crash during cloning.
3. Organization Support: create_github_repo hardcoded the /user/repos API endpoint, causing organizational repositories to be incorrectly requested under the authenticated user instead of their respective namespace.

The Fixes

• get_github_repos() now yields the exact repository "name" to ensure the existence check successfully evaluates.
• get_or_init_repo() now proactively constructs a fallback clone URL (f"https://github.com/{namespace}/{repo_name}.git") to ensure the clone command never crashes.
• create_github_repo() now successfully returns the GitHub API clone_url upon creation.
• Added an optional organization argument to seamlessly support both user and organization /orgs/{org}/repos creation pathways based on the provided namespace.

Testing

• Verified clearcode and model test suites pass locally against the PostgreSQL testing database.

Closes #847