Add missing API endpoints

What changed

New endpoints

• AI responses (get, list, latest)
• DNS blocklist history items (get, list)
• Ports history items (get, list)
• Domain info
• Notification destinations (team, tag, tag group — full CRUD)
• Recurring maintenance periods (full CRUD)
• Status page update templates (full CRUD)
• Tags (create, list)
• Tag groups (full CRUD)
• Additional status page endpoints (create, add/delete monitors, get updates, update updates)
• Additional monitor endpoints (get by URL, add to broken links whitelist, delete/update notification destinations, check summary)
• Application health check snooze/unsnooze
• Cron check definitions sync

New DTOs

• AiResponse, DnsBlocklistHistoryItem, DomainInfo, PortsHistoryItem, RecurringMaintenancePeriod, StatusPageUpdateTemplate, Tag, TagGroup

New properties on existing DTOs

• Check: added averageResponseTimeInMs
• Monitor: added type, portsCheckSettings, dnsBlocklistCheckSettings, aiCheckSettings
• StatusPage: added preventIndexing, addHstsHeader
• CheckType enum: added DnsBlocklist, Ports, Ai

Improved null-safety

• Several DTO fromResponse methods now use ?? null / ?? [] defaults for fields that the API may omit, preventing errors on partial responses (ApplicationHealthCheck, ApplicationHealthCheckHistoryItem, BrokenLink, DetectedCertificate, DnsHistoryItem, DowntimePeriod, LighthouseReport, StatusPage)

Housekeeping

• Removed dev-only test scripts and vlucas/phpdotenv dev dependency
• Added laravel/pint as dev dependency for CI formatting
• Dropped PHP 8.1 from CI matrix
• Updated README with documentation for all new endpoints
• Removed docblock comments from CertificateHealth helper methods (no functional change)
• Minor refactor of OhDearException constructor and ValidationException::getAllErrorMessages()