Choose the self-signed certificate's key type and validity

[excavador]

When no operator certificate is installed the board issues its own: EC P-384, real names, 825 days, renewed 30 days out. Make the key type and validity settings — the daemon already serves RSA, P-256, P-384, P-521 and Ed25519 with a real-handshake test for each. (The renamed-board case is fixed: since firmware v2.33.0 the board reissues its own certificate when its names change.)

What this does not cover: installing a certificate your own CA issued, and renewing one automatically. Both are their own ideas — install your own certificate (shipped in v2.33.0) and ACME against a private CA — because they are what people actually asked for and this one is only about the certificate the board issues itself.

Tracked as SQU-205.

Status: Open