feat: wire domain controller with rdap registration

[zachsmith1]

This pull request introduces significant improvements to domain registration and nameserver modeling, as well as configuration enhancements for refresh and retry behavior. The changes clarify how authoritative nameservers are represented, refactor the registration data model, and add new configuration options for controlling registration data refresh intervals and backoff strategies.

Domain and Nameserver Modeling Improvements

• Added Nameservers and Apex fields to DomainStatus to distinguish between apex domains and delegated subdomains, with clear rules for authoritative NS selection. (api/v1alpha/domain_types.go, config/crd/bases/networking.datumapis.com_domains.yaml)
• Refactored Nameserver to include a list of NameserverIP objects, which capture per-address provenance, and removed the direct Nameservers field from Registration. (api/v1alpha/domain_types.go, api/v1alpha/zz_generated.deepcopy.go)

Registration Data Model Updates

• Added NextRegistrationAttempt field to Registration to track when the next registration refresh should occur. (api/v1alpha/domain_types.go, api/v1alpha/zz_generated.deepcopy.go, config/crd/bases/networking.datumapis.com_domains.yaml)

Configuration Enhancements

• Introduced DomainRegistrationConfig to control RDAP/WHOIS refresh behavior, including refresh interval, retry backoff, jitter, and lookup timeout, with sensible defaults and deep copy support. (internal/config/config.go, internal/config/zz_generated.deepcopy.go, internal/config/zz_generated.defaults.go)

Test and Default Handling

• Updated tests and object defaulting to ensure new configuration fields are initialized and used correctly in domain verification and registration logic. (internal/controller/domain_controller_test.go, internal/config/zz_generated.defaults.go)

[joshlreese]

Looks good. Left a few questions but nothing blocking a merge.