feat(S15P11A705-14): improve draft ticket workflow

[tpals0409]

Summary

• allow users to add and delete server-authoritative draft tickets within 1–20 bounds
• add editable title/description flow, loading spinner, and copyable AI input guide
• group structured source lines into ticket descriptions and prevent blank Jira descriptions
• preserve immutable assignee, role tag, sprint, and confirm-from-stored-draft behavior

Verification

• pytest -q: 35 passed
• ruff check app tests: passed
• python -m compileall -q app tests: passed
• node --check app/static/app.js: passed
• local container build, MCP OAuth import, and /health smoke: passed
• real Hermes planner: independent lines remained separate; structured title/content/completion input preserved description and completion sections

TDD Evidence

• RED: API/UI contracts initially failed because task count changes, loading states, guide controls, source grouping, and malformed source indexes were unsupported
• GREEN: focused API, planner, and UI contract tests pass
• Full regression: 35 passed

Jira: S15P11A705-14