Queue owner: self-spawn through acpx CLI entrypoint

[dutifulbob]

Summary

Make queue-owner startup reliable by self-spawning through the current acpx CLI entrypoint instead of a separate bundled file path.

Problem

Queue-owner startup depended on resolving queue-owner-main.js from build output paths.
That was fragile across build layouts and packaging, and made startup behavior sensitive to where artifacts landed.

What changed

• Switched queue-owner startup to run via:
  • <resolved acpx cli path> __queue-owner
• Added runQueueOwnerFromEnv(...) in a reusable module (src/queue-owner-env.ts).
• Removed the dedicated queue-owner-main build entrypoint and related legacy parsing path.
• Added tests for:
  • spawn arg resolution from symlinked CLI paths
  • queue-owner env payload parsing + missing payload errors

Why this is better

• One entrypoint for CLI + owner startup
• Less packaging/build coupling
• Works consistently for global installs, npx, and symlinked bins
• Smaller surface area (removed duplicate bootstrap code)

Validation

• npm test