A bundle a consumer can only look things up in is a filing cabinet. This adds
the derivation half of what lets one REASON over it: per-document title,
number, parent and references, plus bundle-level resolution of every pointer.
Two rules carry the design. Every fact is marked DECLARED or DERIVED, because
an unmarked heuristic is worse than no heuristic -- a consumer cannot know when
to doubt it. And resolution is a PURE function of the whole document set rather
than a diff, which is what makes rebuild-from-scratch equal an incremental
update by construction: there is no diffing algorithm to prove correct.
An unresolved pointer is kept and reported, never dropped: while a bundle is
built up over several rounds, pointing at something not dropped yet is the
normal state, and the dangerous version of it is the one that leaves no trace.
Symmetrically, a parent our own grammar could never admit (4.2 -> 4, a bare
integer) is not emitted at all -- an unresolved list that never clears is one a
consumer learns to ignore.
45 new tests; suite 615 -> 660.
