BJ-9: Add JiraService — issue-oriented Jira Cloud API surface#

Problem#

The AgentSDE pipeline needs a service to interact with Jira Cloud issues (comments, transitions, labels, assignee, priority, links, search). Without it, Jira-backed projects cannot be automated end-to-end.

Task / Link#

Closes #549

Changes#

• Add JiraService with 11 issue-oriented methods backed by Jira Cloud REST v3: postComment, editComment, transitionIssue, getTransitions, addLabel, removeLabel, setAssignee, setPriority, linkIssues, searchJql, getIssue
• Private request() helper attaches Authorization: Bearer <token> from JIRA_AUTH_PROVIDER; retries once on 401 (token refresh) and once on 429 (honouring Retry-After)
• Add JiraModule with factory providers for JIRA_AUTH_PROVIDER (stub until Atlassian OAuth lands) and JIRA_SERVICE
• Register JiraModule in AppModule
• Add JIRA_CLOUD_ID (optional) to config schema, .env.example, and CLAUDE.md
• 24 unit tests covering all methods, 429 retry, 401 refresh, missing-config error, and empty-result paths

Notes#

• JIRA_AUTH_PROVIDER is a stub (returns null) until the Atlassian OAuth module (BJ-3/4/5) lands; both JIRA_AUTH_PROVIDER and JIRA_SERVICE will be null until then — consumers must treat Jira support as optional
• JIRA_CLOUD_ID is made optional in the config schema (not required()) to allow startup without Jira credentials

Testing#

• 24 unit tests in src/jira/jira.service.spec.ts — all pass
• npm run lint — zero warnings