counterexample for array ordering

Arrays in real atproto records almost universally lack index-bound significance. That is: a selector for a record's array element at index=0 is almost never useful.

there are a couple of records in tangled that make use of array ordering!

• the pull record makes use of ordering of "rounds", to denote sequential revisions of a patch. the ordering is important to track patch evolution.
• (to be implemented) the profile record will soon use the ordering of pinned repos in the lexicon to dictate the ordering of pinned repos in the UI