Allow ACME account keys to be configured via config file to maintain
the same Let's Encrypt account across deployments. Add DecodePrivateKey
function with PEM block type constants to support EC, RSA, and PKCS8
key formats. When no account key is provided, fall back to generating
a new one with a warning.
Signed-off-by: Bryan Frimin <bryan@getprobo.com>
Introduced ErrHTTPChallengeRequired as a sentinel error and updated the
renewal flow to use errors.Is() for type-safe error checking instead of
string matching.
Signed-off-by: Bryan Frimin <bryan@getprobo.com>
