Add advanced status page controls

[jusso-dev]

Problem

Status pages for real organizations need private access, localization, stronger branding, and embeddable status indicators.

Scope

• Add password protection and IP allowlist for private status pages.
• Add custom domain support docs and verification endpoint.
• Add i18n/custom text support for public page copy.
• Add status badges, widgets, and embeddable JSON endpoints.
• Add custom CSS escape hatch for advanced users.

Acceptance criteria

• Private pages can require a password or source IP allowlist.
• Custom domain setup can be verified through an API endpoint.
• Status pages can render configured locale strings.
• Badges/widgets expose current component or page status.
• Tests cover access controls and public widget response shape.

Dependencies

• Public status page MVP.
• Status page subscribers and announcements.

Notes

This issue is part of the GoUpTime product roadmap.