Run independent factory issues concurrently with bounded developer lanes

[neubig]

The current recipe stops development whenever any PR awaits review, so an independent backlog still runs one issue at a time.

Ready for dev.

Acceptance criteria:

• Run two or more developer lanes using the existing Automation Service scheduling/concurrency controls and the canonical issue-to-PR workflow.
• Give each lane deterministic, disjoint issue ownership; do not start duplicate implementations or change ownership while runs are active.
• Respect explicit issue dependencies before development and keep the number of open implementations bounded.
• Use GitHub's existing branch-update operation to refresh stale PR bases and require independent acceptance of the new head.
• Preserve identical behavior in local/Docker workspaces and per-role gateway/profile secret boundaries.
• Verify overlapping development and independent review in the software factory demonstration under a bounded machine resource budget.

[github-actions]

⚠️ Not yet ready-for-dev

This issue does not yet meet the readiness criteria, so the
ready-for-dev label has not been applied (or has been removed).
The criteria are type-specific:

Bug reports (bug label):

• The ### Actual Behavior section must describe reproducible steps
  and include a command such as uv run pytest, pytest, python,
  pip, npm run, or node.
• An ### Acceptance Criteria section with at least one checklist item (- [ ] ...).

Enhancements (enhancement label):

• A ### Desired Behavior section.
• An ### Acceptance Criteria section with at least one checklist item.

What is missing:

• The issue has neither the bug nor enhancement label, so its readiness criteria cannot be evaluated. Add the appropriate label.

Edit the issue to address the gaps and the ready-for-dev label will be
applied automatically.

This is an automated readiness check posted by a workflow.