Add fully decentralized verifiable issuer use case

[msporny]

We need to add the following fully decentralized verifiable issuer use case to the specification:

The National College Board would like to provide a verifiable credential to each State College to confirm that they would accept degrees issued by a specific college as legitimate proof of education. Since the National College Board does not operate technical infrastructure with high-availability guarantees, it wants to distribute this information in a way that can be presented by the State College issuer or the holder of a particular degree when presenting that degree to a verifier.

The minimum viable data model for achieving this use case for an issuer could be something like the following:

{
  "@context": [
    "https://www.w3.org/ns/credentials/v2",
    "https://www.w3.org/ns/credentials/examples/v2"
  ],
  "type": [
    "VerifiableCredential",
    "VerifiableRecognitionCredential"
  ],
  "issuer": "did:web:recognizer.example",
  "validFrom": "2025-01-01T00:00:00Z",
  "validUntil": "2030-01-01T00:00:00Z",
  "credentialSubject": {
    "id": "did:web:issuer.example",
    "type": "RecognizedIssuer",
    "recognizedBy": "did:web:recognizer.example", /// hmm...
    "recognitionCriteria": [{
      "type": "Issuance",
      "validFrom": "2021-01-01T00:00:00Z",
      "validUntil": "2026-01-01T00:00:00Z",
      "credentialSchema": {
        "id": "https://recognizer.example/schemas/degrees/bachelors.json",
        "type": "JsonSchema",
        "digestMultibase": "uELqXcnlc5P7xp1u-5uJRDYKvc9FnJ5YLa5iAszyJ518b"
      }
    }, {
      "type": "Issuance",
      "validFrom": "2025-01-01T00:00:00Z",
      "validUntil": "2026-01-01T00:00:00Z"
      "credentialSchema": {
        "id": "https://recognizer.example/schemas/degrees/masters.json",
        "type": "JsonSchema",
        "digestMultibase": "uELYKvc9FnJ5YLa5iARD18bszyJ5qXcnlc5P7xp1u-5uJ"
      }
    }]
  },
  "proof": {
    "type": "DataIntegrityProof",
    "created": "2025-08-10T20:08:22Z",
    "verificationMethod": "did:web:recognizer.example#issuance-key-1",
    "cryptosuite": "ecdsa-rdfc-2019",
    "proofPurpose": "assertionMethod",
    "proofValue": "z36XPGByaH3rvtKfwoEQXsnUXUAjwd2Ceiqke1GPfjAPAFYoXKo5ftPdwE7QZ8Mw22SC5LSRQg1d8bhe3252hYJoH"
  }
}

The minimum viable data model for achieving this use case for an verifier could be something like the following:

{
  "@context": [
    "https://www.w3.org/ns/credentials/v2",
    "https://www.w3.org/ns/credentials/examples/v2"
  ],
  "type": [
    "VerifiableCredential",
    "VerifiableRecognitionCredential"
  ],
  "issuer": "did:web:recognizer.example",
  "validFrom": "2025-01-01T00:00:00Z",
  "validUntil": "2030-01-01T00:00:00Z",
  "credentialSubject": {
    "id": "did:web:verifier.example",
    "type": "RecognizedVerifier",
    "recognizedBy": "did:web:recognizer.example", /// hmm...
    "recognitionCriteria": [{
      "type": "Verification",
      "validFrom": "2021-01-01T00:00:00Z",
      "validUntil": "2026-01-01T00:00:00Z",
      "presentationSchema": {
        "id": "https://recognizer.example/presentation-schemas/degrees/bachelors.json",
        "type": "JsonSchema",
        "digestMultibase": "uELqXcnlc5P7xp1u-5uJRDYKvc9FnJ5YLa5iAszyJ518b"
      }
    }, {
      "type": "Verification",
      "validFrom": "2025-01-01T00:00:00Z",
      "validUntil": "2026-01-01T00:00:00Z"
      "presentationSchema": {
        "id": "https://recognizer.example/presentation-schemas/degrees/masters.json",
        "type": "JsonSchema",
        "digestMultibase": "uELYKvc9FnJ5YLa5iARD18bszyJ5qXcnlc5P7xp1u-5uJ"
      }
    }]
  },
  "proof": {
    "type": "DataIntegrityProof",
    "created": "2025-08-10T20:08:22Z",
    "verificationMethod": "did:web:recognizer.example#issuance-key-1",
    "cryptosuite": "ecdsa-rdfc-2019",
    "proofPurpose": "assertionMethod",
    "proofValue": "z36XPGByaH3rvtKfwoEQXsnUXUAjwd2Ceiqke1GPfjAPAFYoXKo5ftPdwE7QZ8Mw22SC5LSRQg1d8bhe3252hYJoH"
  }
}