Security: clear remaining CodeQL baseline alerts

[ncihxaonn]

Summary

• reject lookalike cookie domains and accept only exact X/Twitter domains or their subdomains
• read Git worktree metadata through a stable, non-symlink file descriptor
• add a regression test for cookie-domain validation

Validation

• typecheck
• lint
• 248 tests passed, 7 skipped
• build
• release verification
• Codex schema generation and drift check
• package dry run
• production dependency audit: no known vulnerabilities