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

crates/ledger-mcp/handbook/tracing-figures.md

@@ -6,3 +6,4 @@
 - Never guess, and never look for the books' files: the tools are the evidence.
 - books.verify checks the books end to end when a number looks wrong or a human asks whether the books are intact.
 - A member's odd cent: closes, the statement of members' equity, the K-1 worksheet and the viewer split earnings among the members one running way. Each close gives a member their share of everything closed to the same members and shares so far, to the cent (odd cents by largest remainder, ties to the member listed first when that count began), less what earlier closes gave them, so no member is ever a cent from their exact share. Earnings not yet closed are split the way their close will split them, so a member's capital on a day never changes when its month is closed. books.close_period's members shows each member's part, running total and exact share; the first close that posts may carry a one-time correction of the rounding left by closes made under an earlier rule (a cent or so per member; each member's this_close shows it) (books.list_periods' close_rule names each close's rule). A change of members or shares starts a new count.
+- A member's odd cent on the tax-basis K-1 (books.export_cpa_package's k1-tax-basis-capital.csv): each contribution's built-in gain, property without a basis and prepaid, and each distribution's property, are split among the members with a part in that entry (by their property in it, or what each took) the same running way, one count for each set of such members, from the books' first entry in date order whatever the span. So an entry can give a member a cent more or less than its own split would, because of an earlier entry by the same members; never a cent to a member with no part in it. A reversal takes its original's cents back out, so an entry's cents are the same in every span.