One token slot, remote cursors and local ones

A list that pages from a server holds a continuation: String?. When the same list must also page a locally sorted or shuffled ordering, the cheapest correct move is to keep one slot and make the local cursors fit in it, rather than adding a parallel "local page index" that every consumer then has to know about.

Routing happens twice: the collection id says local or remote, and the token's prefix says which local mode.

// adapted: names generalized, page size hoisted; encoding as written
"SHUFFLE0_[7,2,19,4]"   // shuffle: page number, then the whole shuffled position list as JSON
"ASC1735689600000"      // oldest-first: the timestamp of the last row read
"DESC1735689600000"     // newest-first: same, other direction
"TITLE3"                // stable order: a page offset
"CUSTOM_ORDER3"         // stable order: a page offset