Review follow-ups on the tier-shift fix. The table moves to a module-level
RELATIVE_UNITS: it is constant, so rebuilding it per call was pure garbage on
a path that runs once per rendered timestamp across a virtualized feed.
Its ascending order is load-bearing and was unstated — sorting it largest-first
would make every timestamp under a year read "just now", silently, the same
shape as the bug this branch fixes. It is now documented and asserted, and the
suite derives its tier coverage and translation checks from the table itself
rather than from its own case list, so a new tier cannot slip in uncovered.
The audit log read the empty string for an unreadable date as a value and
rendered a blank cell; it now uses the `|| "—"` idiom the channel table
already uses, so missing and unreadable dates look alike.
A `truncate` (nowrap) cell in the auto-layout DataTable sizes the whole table to
its widest row, so one long summary/change stretched the table past the card and
the row rules bled into the page. break-words keeps every row inside the card.
peter