BREAKING: Removed Get-InfisicalProjects, Get-InfisicalEnvironments, Get-InfisicalFolders, Get-InfisicalTags, Get-InfisicalSecrets, and Get-InfisicalCertificates. Their list behavior is now the default parameter set on the singular cmdlets; supplying the identity parameter switches to single-record retrieval. No back-compat aliases.
Fix: SignCertificateBySubscriber endpoint resolved to /api/v1/pki/subscribers/{subscriberName}/sign-certificate (was /pki/pki-subscribers and /cert-manager/pki-subscribers, both 404).
Added Get-InfisicalPkiSubscriber (List/ByName), InfisicalPkiSubscriber model, DTOs, mapper, and InfisicalPkiClient.ListPkiSubscribers/GetPkiSubscriber. MAML help refreshed for all consolidated cmdlets with 2 straight-line + 1 OrderedDictionary splat examples each. README extended with extension guide. CHANGELOG updated. 230/230 tests pass.