Fix/120 case insensitive repo removal

[enjoyandlove]

Summary

Fixes a bug where removing a GitHub repository via webhook could silently fail if the repo name was stored with different casing than what the webhook payload sent. Two changes:

1. On add: repoFullName is now normalized to lowercase before insert, so all new rows are stored consistently.
2. On remove: the UPDATE query now uses LOWER(repo_full_name) = LOWER(:name) via createQueryBuilder, making the lookup case-insensitive and matching rows regardless of how they were originally stored.

Related Issues

Fixes #120

Type of Change

• Bug fix

Testing

• Manually verified that removing a repo whose name is stored in mixed case (e.g. Org/Repo) is correctly matched and cleared when the webhook sends org/repo (all lowercase) or any other casing variant.
• Existing tests pass.

Checklist

• I have read the Contributing Guide
• Code builds without errors
• New and existing tests pass (if applicable)
• Documentation updated (if applicable)
• No unnecessary dependencies added