Add missing resources from our API to the SDK

[mattiasgeniar]

Why

The Oh Dear API has introduced several new endpoints since v4.4.1 that the SDK didn't support yet. This PR adds support for all missing API endpoints and improves the robustness of existing DTOs.

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()

Risks

This PR is fully backwards compatible with v4.4.1. Specifically:

• No existing methods removed or renamed — all public methods from v4.4.1 remain unchanged
• No constructor signature changes — OhDear constructor is identical
• No existing DTO properties removed — new properties on existing DTOs all have default values (null, false, '', []), so existing code that constructs DTOs manually will continue to work
• No dependency changes — runtime dependencies (saloonphp/saloon, saloonphp/pagination-plugin) and their version constraints are unchanged
• No PHP version requirement changes — still ^8.1
• Null-safety improvements are non-breaking — adding ?? null defaults to fromResponse methods only makes the DTOs more tolerant of partial API responses, not less

The only changes to existing code are cosmetic (removed docblocks, reformatted exception constructor, simplified getAllErrorMessages()), none of which affect the public API.