feat: adds sigstore-certificate-maker poc

[ianhundere]

closes #10

[amber-beasley-liatrio]

running through the readme

make target "check" doesn't exist?

[ianhundere]

ah, i used the go template which was completely broken. you'll see that even with the first commit things didn't work, so i blew away most of it.

https://github.com/liatrio/sigstore-certificate-maker/actions/runs/11688873648

the primary thing here to review is main.go:

• https://github.com/liatrio/sigstore-certificate-maker/blob/ee5fadc0ff3d089097065f2fd41528900688ef76/main.go

will move this to the following repos when i get a definitive answer from the sigstore community:

• https://github.com/sigstore/fulcio
• https://github.com/sigstore/timestamp-authority

[amber-beasley-liatrio]

I got (switch smells correct)

openssl x509 -in intermediate.pem -text -noout
Certificate:
    Data:
        Version: 3 (0x2)
        Serial Number: 2 (0x2)
        Signature Algorithm: ecdsa-with-SHA256
        Issuer: CN=https://blah.com
        Validity
            Not Before: Nov 10 13:14:09 2024 GMT
            Not After : Nov 10 13:14:09 2124 GMT
        Subject: O=Liatrio, CN=Intermediate CA
        Subject Public Key Info:
            Public Key Algorithm: id-ecPublicKey
                Public-Key: (256 bit)
                pub:
                    04:30:45:5f:a2:bb:23:c7:55:da:82:2c:a7:2f:9a:
                    f9:93:a5:f7:6e:b1:d9:a3:15:83:c2:31:36:3e:f6:
                    0e:0a:76:15:e9:70:f1:8c:49:ff:bd:e7:eb:4a:61:
                    8d:5a:f2:52:15:08:9e:0f:0a:72:77:b8:b8:7a:19:
                    17:e1:11:bc:e1
                ASN1 OID: prime256v1
                NIST CURVE: P-256
        X509v3 extensions:
            X509v3 Key Usage: critical
                Certificate Sign, CRL Sign
            X509v3 Basic Constraints: critical
                CA:FALSE
            X509v3 Subject Key Identifier: 
                44:37:0E:93:7C:1E:98:19:66:D2:CA:29:62:F7:C0:F6:2D:91:9A:EF
            X509v3 Authority Key Identifier: 
                C3:18:CC:12:EC:9B:7E:E4:0A:3F:DB:7E:D9:97:F6:B5:2A:26:D4:64
    Signature Algorithm: ecdsa-with-SHA256
    Signature Value:
        30:45:02:20:72:1a:f6:3d:92:42:8c:90:10:0d:8b:f2:9c:01:
        36:89:39:50:84:0b:1e:c2:8b:27:d4:78:87:4e:7b:8d:77:be:
        02:21:00:bd:88:84:57:93:de:7b:0e:c1:e8:83:5f:73:8a: