fix(domainregister): compare email domain quota numerically

[tzh476]

Summary

Fix #1994 by normalizing the email-domain quota values before comparing them. This prevents numeric strings such as 7 and 20 from being compared lexicographically and incorrectly tripping the quota-limit path.

The PR keeps the regression test in its own commit, followed by the fix commit, so the test can be cherry-picked independently.

Duplicate check

• Checked open and closed PRs for 1994, domain quota, and Email Domain quota.
• Found only old merged PR feat(domreg): In domain registration, check that user has domain quot… #864 from 2020; I did not find an open or closed duplicate for this string-comparison regression.

Validation

• npx tsc -p src/tsconfig.spec.json --noEmit
• npm run lint -- --quiet
• git diff --check HEAD~2..HEAD

Not run locally:

• npm run ci-tests: this environment does not currently have a working Firefox/Karma browser runtime available, so I kept validation to the static checks above instead of reporting full CI coverage.

AI-use disclosure

This contribution was prepared with AI assistance.

• Model/agent: OpenAI Codex, GPT-5 based coding agent.
• Harness: Codex desktop/local shell environment; exact harness version not shown in the session.
• Tools used for this PR: local shell commands, npm/TypeScript/Angular lint tooling, GitHub CLI.
• Available installed connector/plugin classes in the session included GitHub, Gmail, Chrome/browser, and document/data tooling; only local shell and GitHub CLI were used to prepare and submit this PR.
• AI touched the issue analysis, regression test, implementation, validation commands, commit preparation, and PR description.
• The account owner reviewed/approved submission in the Codex task before this PR was opened.