A `make format` sweep re-lays-out already-committed files without
changing a single token, so it cannot change what renders. The browser
verification guard still demanded a fresh receipt for it, which would
mean recording routes, viewports, states and interactions nobody
exercised in order to describe a diff with no visual delta. A guard that
can only be satisfied by an untrue receipt teaches people to write
untrue receipts.
Exempt a path only when its new content is byte-identical to prettier's
output for its committed content. That is provable, not a judgement
call: if the two match, the sole difference from HEAD is layout.
Fails closed everywhere else -- added or deleted files, unreadable
blobs, prettier missing, or any non-identical output all fall through
and still require the receipt. A reformat that also changes a value is
covered by a test and still blocks.
