The read routes leave out a room, shade, group or linked shade that
doesn't fit the 3 KB unit, without telling the client (KNOWN_ISSUES.md).
test_snapshot_limits fills a snapshot with the largest possible items and
checks every read document written with the real unit is identical to
the same document written with an unlimited one. The largest item, a
shade, is 1,097 bytes. The unit is now SNAPSHOT_UNIT_SIZE in
ModelSnapshot.h, used by Web.cpp and the tests.
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
