fix(k1 tax basis): odd cents of property basis run cumulatively (B-36, D-38)

The tax-basis K-1 shared each entry's built-in gain, property without a
basis, prepaid at book and property distributed among the members entry
by entry, every tied odd cent to the first member: three equal odd-cent
properties contributed 50/50 left the members three cents apart.

Apply D-38's rule (the closes' cumulative largest remainder, through
kernel::apportion_cumulative): tax_capital::RunningSplit keeps each
member's exact running share, rounds the running shares afresh to the
cent and hands out the change, so no member's running share is ever a
cent from exact and tied cents alternate. A negative running whole is
rounded as its magnitude, a zero one by the sign of the whole just
split, so a run of losses mirrors its gains part for part. Exact running
shares are taken to ten places before rounding: a sum of Decimal thirds
can sit a hair under its cent (the law found 399.93 as 399.9299...).

tax_capital::entry_parts runs the splits over every posted entry from
the books' first, in date order, whatever span is asked for, with one
count per set of members with a part in the entry: a member never takes
a cent of an entry they had no part in (Item L's capital contributed is
the basis of the property that member contributed), and the count never
restarts, since its weights are each entry's own amounts, not shares.
An entry's reversal takes its original's split back out of the count
(RunningSplit::unsplit), so an entry's cents are the same in every span
and next year's beginning is this year's ending. The K-1's per-entry
lines come from k1::entry_lines, which k1_detail now uses too.

The book property each member contributed in an entry stays split entry
by entry (each member's property must stay within their own credit);
B-36 says so.

Tests: tied_odd_cents_of_property_basis_run_cumulatively (fails on the
per-entry split: 665.86 / 665.83); a_member_outside_an_entry_never_
takes_its_cents (three members; fails with one count for all members),
an_entrys_odd_cent_is_the_same_in_every_span (a reversal across the
span's start; fails with the count carried span by span or the reversal
not taken out), the_split_runs_in_date_order (fails in posting order);
the law a_running_split_never_drifts_a_cent (5,000 cases: the
largest-remainder rounding of exact integer shares, ties to the first,
and the negated run mirrored; fails with ties to the later member or a
zero running whole rounded as a gain); unit tests for one split,
alternating ties, a member outside a split, the mirror at zero, unsplit
and the thirds case; bookspec example partnership-k1-tax-basis-odd-cents.
rules.md B-36, the handbook (tracing figures), STATUS, testing.md and
verification.md updated.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01T3gXMVt7XJPi6ens1or9Dj

docs/verification.md

@@ -267,6 +267,20 @@ The P3 odd cent (defect 17; rules.md B-13; D-10, D-38) adds three laws:
       `Apportion.allocW_cumulative_drift` (the two together): any number of
       members, any amounts
     - property `members_capital_never_drifts_a_cent_from_their_share`
+    - the tax-basis K-1's running split (B-36 with D-38, 2026-10-22),
+      whose splits each carry their own weights, so the exact running
+      share is a sum of quotients and Decimal's division can leave it a
+      hair under the cent it is (`tax_capital::RunningSplit` takes it to
+      ten places first): property `a_running_split_never_drifts_a_cent`
+      (`ledger-core/tests/tax_capital.rs`, checked against the
+      largest-remainder rounding of exact integer shares, and a loss
+      against its gain); its kernel step is `apportion_cumulative`,
+      proved above. The worksheet keeps one per set of members with a
+      part in an entry, in date order whatever the span
+      (`tax_capital::entry_parts`; tests
+      `a_member_outside_an_entry_never_takes_its_cents`,
+      `an_entrys_odd_cent_is_the_same_in_every_span`,
+      `the_split_runs_in_date_order`)
 22. **A member's capital on a day never moves when its period is closed.**
     The statement of members' equity gives each member, of the earnings not
     yet closed, what the count's next close would give them; closing moves