feat(jira): orchestrate authored subtask graphs (#574)

[ayushtr-aws]

Adds the Jira entry point for the shared orchestration engine. This is PR 1 of 3 for #580; #726 builds on this branch.

Area

• cdk - infrastructure, handlers, constructs
• agent - Python runtime / Docker image
• cli - bgagent client
• docs - guides or design sources (docs/guides/, docs/design/)
• tooling - root mise.toml, scripts, CI workflows

Related

Closes #574

Parent: #580

Stack: #725 -> #726 -> #727

Changes

• Fetch authored Jira subtasks and blocker relationships as a channel-neutral orchestration graph, including pagination and explicit API-error handling.
• Seed and release Jira child work through the shared DAG executor while preserving issue identity, credentials, owner, repository, and branch metadata.
• Route orchestrated Jira child iterations back through the shared reconciliation and dependent-restack path.
• Add graph-source, webhook, release, store, construct, and documentation coverage.

Verification

• mise run build on the stack head
• Focused and full CDK suites (178 suites, 3,554 tests on the stack head)
• GITLEAKS_RANGE=origin/main..HEAD mise run security:secrets:range

Acknowledgment

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of the project license.