phsl / new-api

* fix(channel): debounce inline priority updates

* fix(channel): commit spinner edits only on Enter or focus leave

Blurring the inline edit input to the +/- buttons flushed the pending
priority update immediately, bypassing the container focus-containment
check and defeating the debounce. Commit now happens via the container
blur handler or explicitly on Enter. Add unit tests for the priority
update scheduler.

* fix(channel): preserve row identity when priority updates reorder channels