[Zalgia-Saga]

ci: fix bundle size badge, link-check condition and uptime content validation

• Body:
• Derive bundle size badge thresholds from the limit enforced in CI
• Use valid hex colors for the bundle size badge SVG fill
• Remove the always-true if condition on the link-check internal-links job
• Make the uptime check's content validation fail when branding is missing

Closes #665
Closes #666
Closes #667
Closes #668

[drips-wave]

@Zalgia-Saga Great news! 🎉 Based on an automated assessment of this PR, the linked Wave issue(s) no longer count against your application limits.

You can now already apply to more issues while waiting for a review of this PR. Keep up the great work! 🚀

Learn more about application limits