merge: P6, the evidence pipeline (branch P6, checkpoint ce366408)

The last of the paused branches, from its "not for merge" checkpoint:
extraction in ledger-import (text, pages, page images; capped, caught),
journaled as attachment.text_extracted; dedup by hash with
books.find_attachment and books.consolidate_duplicates; annotations and
books.set_entry_settles; the company record categories; the two fuzz
targets; feature attachment_text. Nineteen files conflicted with the
four P4b merges, resolved as plan 8.0.2 says: P6 retakes schema 18 (it
had taken 16, which S4.3 holds; S5 holds 17); the tool table is 129 and
the destructive count 31; both sides' appends kept with their seams
restored; one B-27 paragraph naming every feature; in the old-books
fixture P6's hand-written reimbursement is entry 7 (its ids collided
with S4.3's invoice); the replay fuzzer's list gains S7's
invoice.written_off; S4.3's issued-PDF test expects the extraction
record P6 journals right after a filing.

One integration defect between S7 and P6, found by the arap property
test and fixed here: under P6's dedup, a write-off whose evidence bytes
were filed already (the same collection letter for a second write-off of
the same invoice) was refused only after its entry had been journaled,
at the final link to the invoice ("already linked"). The write-off now
resolves the dedup before anything is journaled and keeps a link the
record already has to the invoice instead of refusing it; an explicit
existing_attachment_id already on an entry is still refused (S7's
one-receipt-once rule). P6's gate never ran before the pause; it runs on
main after this merge, and its ledger-store -> ledger-import dependency
is the open review point (plan 8.0.1).

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01HS8WZziDnyxunC23MUxrLp

crates/ledger-store/tests/arap_props.proptest-regressions

@@ -6,3 +6,4 @@
 # everyone who runs the test benefits from these saved cases.
 cc 704ab49c9bea84359475c3afa56c3354275a353670fc71156fba151f846f4f73 # shrinks to first = [Create(false, 0, 1), Create(false, 0, 1)], then = [Close(1), Hand(false, 1)]
 cc f678814ec34db3abef40116e17e562fe5abe652c09f12600e19841beaf9d6fe6 # shrinks to first = [Create(false, 0, 13902), Settle { a: 0, b: 0, n: 0, cash: 6676, discount: 551, fee: 0 }], then = []
+cc fade94264cb4e769ef3d72573baff01fc2f78483a32e8424e56251d96c4af57e # shrinks to first = [Create(true, 0, 27747), WriteOff(0, 0, 1), Create(false, 0, 1)], then = [Create(false, 0, 7), WriteOff(3, 66, 2761)]