closes: a run of members closes splits cumulatively

Each close into members' capital rounded on its own, ties to the
earlier member, so twelve monthly 50/50 closes of odd-cent income could
leave one member several cents ahead of half the year (docs/testing.md
#12, found with the members' equity fix).

- CloseTo::Members now splits cumulatively over a run (closes back to
  back with the same members and shares): each close gives a member
  allocate(run total so far) - allocate(run total before). Periods
  record their close order and a cumulative close's members and net
  (Period::close_seq, member_close) so the next close continues the run
  and replay recomputes it exactly. A close to anything else, or other
  shares, ends the run.
- Journaled "rounding": "cumulative". The per-close rule is kept as
  CloseTo::MembersPerClose for closes journaled "largest_remainder";
  older closes still replay with the last member absorbing it.
- Lean: runPart_telescopes (a member's total from a run is their
  allocation of the run's total) and closePart_total (each close hands
  out exactly its net), audited to the standard axioms.
- Tests: hand-computed three one-cent months (per close A 0.03 / B 0;
  cumulative A 0.02 / B 0.01), a run ending, a property that each member
  stays within a cent of their share (fails on the per-close rule), and
  a store contract that each rule journals and replays as itself.

Wanderland's books have no closes yet, so all of theirs use the new rule.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX

docs/verification.md

@@ -124,6 +124,13 @@ sequence of commands, of any length**:
     other shares were rounded, and only the last share changes.
     - Kani `plug_last_sums_exactly` · Lean `plugLast_total`,
       `plugLast_keeps`
+17. **A run of member closes telescopes**: each member's total from a run
+    of cumulative closes is their allocation of everything the run closed
+    (so its rounding is one allocation's, never a sum of them), and each
+    close hands out exactly its net, for any allocation whose parts sum to
+    the whole (rules.md B-13).
+    - Lean `runPart_telescopes`, `closePart_total` · property
+      `each_member_stays_within_a_cent_of_their_share`
 
 ## What the proofs found