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-mcp/handbook/format-upgrade.md

@@ -7,3 +7,5 @@
 - Before it upgrades, the server makes a backup of the books, their vault and keys included, and proves it whole; a backup that can't be made or proven upgrades nothing. Then the books move to the new format in one step, on the record.
 - After the upgrade an older version of wanderbooks can't open these books; the backup made first keeps them as they were. Going back is the owner's choice, never yours.
 - This upgrade is `documents_v2`: invoice numbers, terms and line accounts (S4), sent records (S5), payments that settle several documents with early-payment discounts and a processor's fee (S6), and write-offs (S7). Until it is given, those writes are refused and everything else works as before.
+
+- The journal features an upgrade can add: `members_cumulative`, `account_renamed`, `require_tax_category`, `tax_categories_gain_exempt`, `disposal_before_service`, `depreciation_catch_up`, `party_creditors`, `payment_instruments`, `vendor_1099_decisions`, `schedule_convention`, `month_reposting`, `asset_basis`, `projects`, `document_line_projects`, `document_standing`, `documents_v2`, and `attachment_text` (P6: a filed file's extracted text, what a human annotated of it, and the entries a payment settles). All are declared at once; a version that doesn't know one stops at the declaration instead of misreading the books.