test: add unit tests for attestation type processors (JUnit, Snyk, SonarQube, Jira)

[MaximumTrainer]

Background

Four attestation type processors were added but have no test coverage:

• JunitAttestationProcessor — parses JUnit XML, sets PASSED/FAILED
• SnykAttestationProcessor — parses SARIF/Snyk JSON, counts vulnerabilities
• SonarAttestationProcessor — reads SonarQube quality gate status
• JiraAttestationProcessor — validates Jira issue key format

Tasks

• Create JunitAttestationProcessorTest with sample passing and failing JUnit XML
• Create SnykAttestationProcessorTest with SARIF and Snyk JSON formats (0 vulns = PASSED, >0 = FAILED)
• Create SonarAttestationProcessorTest with OK and ERROR quality gate responses
• Create JiraAttestationProcessorTest with valid (e.g. PROJ-123) and invalid keys
• Test malformed input → FAILED with error details in each processor

Files

• backend/src/main/kotlin/com/factstore/application/attestation/
• backend/src/test/kotlin/com/factstore/application/attestation/ (create directory)