feat: Target affect chunks only for invalidation after edit operations

[afonsobspinto]

Closes https://metacell.atlassian.net/browse/NA-716

1. do action A (f.e. delete node)
2. action A invalidates the cache
3. We pull all the visible chunks again from the backend
4. while the pulling is still hapening, we click undo
5. The undo request is queued but only processed when the other fetching finishes. (which can take a few, noticeable seconds)

To solve it we narrows the stale browse surface to affected cells and makes remaining browse traffic lower browser/network priority, so edit requests do not compete as heavily with large node/list bursts.

• The main change is replacing broad CATMAID spatial skeleton browse-cache invalidation with targeted cell invalidation.

  • Delete invalidates only deleted node, parent, and direct children.
  • Split invalidates the split subtree plus the former parent.
  • Merge invalidates the deleted/losing segment nodes plus merge endpoints.

• CATMAID node/list browse fetches are marked low priority with fetch(..., { priority: "low" })

• Fixes regression on merge with non-inspected skeleton that was pulling the full skeleton before the merge