`pcb/update-component` attached the whole `:objects` map of a deleted
component to every `mod-component` change, so a single component swap
re-sent thousands of shapes that the same batch already carried as
shape changes. In one measured swap the 49 maps with objects were 94%
of the request (6.3 MB), and only 27% of the 4.275 shapes they carried
differed from what the server had.
Now `mod-component` carries component metadata only, and shapes inside
a component travel as `:mod-obj` changes scoped with `:component-id`,
which is what the component sync already emits. An absent `:objects`
key means "leave the stored shapes alone", only an explicit `nil`
drops them, so metadata-only changes cannot wipe a deleted component.
The two repairs that fix shapes inside a component (shape-ref cycle
and duplicated swap slot) now emit one `:mod-obj` per shape; the two
that move or clear the `:objects` key keep the whole-map write behind
the new `:objects? true` option.
Same swap on the measured file: 6.328.307 to 382.571 bytes.
AI-assisted-by: space-bunny
05e03e2673