v2.0.0-beta.2 — propagation fixes (next channel)

Next-channel prerelease. Install: rbox upgrade --channel next or curl -fsSL https://rbox.to/next/install.sh | sh.

Fixed

• Background sync no longer re-rings its own doorbell: the Linux git watcher ignores rbox's own bookkeeping clicks, ending a no-op push loop (~3s cycle, both Linux hosts).
• A folder with unfinished git work (e.g. a paused merge on another machine) now costs milliseconds per sync instead of ~9 seconds — field-proven 9,381ms → 8ms.
• Unchanged git repos skip the per-repo work queues on both push and pull.

Added

• Propagation measurement rig with per-hop timing and exact sequence correlation.
• rbox status names a degraded file-watcher outright.