Encrypted PKCS#8 private keys are decrypted during staging using the
provided password. The decrypted key is stored for Traefik (which needs
cleartext PEM). Unencrypted keys continue to work without a password.
- CertificateManager.stage() accepts optional keyPassword
- DockerCertificateManager handles EncryptedPrivateKeyInfo decryption
- UI: password field in upload form (vendor CertificatesPage)
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>