docs(handbook): the invoices-and-bills procedure, whole (P4b S4.5)

Step 1 now covers the issue: preview first (nothing written, the DRAFT PDF,
an abandoned preview uses no number), confirm only after the human has
seen it, the filed issued copy that a later look never replaces,
quantities and prices, the PO, and the snapshot of the customer at issue.
Step 6 is the CPA's list: agings tied to 1200 and 2000, sequential numbers
with voids visible, bills on their real accounts with the vendor's number
and no duplicate, card payments identified for 1099-NEC, deposits as
liabilities, light governance by decision.

A {documents_v2} placeholder (handbook::section_with, the server's
documents_v2 feature test) says "your books have not declared documents_v2
yet" before the owner's upgrade and what is on after it; no other section
changes. Parity, testing (with the For-P12 paragraph) and mcp-interface
notes for S4.5.

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

docs/mcp-interface.md

@@ -2254,7 +2254,14 @@ snapshots; see plan 8.2 S4.
   back as a handed file (`pdf`: run its download): re-created from the
   books as of the day, each standing payment on its own line with its
   date, method and reference, stamped PAID (with the day), PARTIALLY
-  PAID, PAST DUE or VOID (P4b S3); refused for a bill.
+  PAID, PAST DUE or VOID (P4b S3); refused for a bill. The page prints
+  the invoice's own number, terms (an early discount reads in them), the customer's PO,
+  each line's quantity beside its price, the customer as at issue
+  (contact, billing address, phone, email, a Ship-to block), the
+  company's email, website, ways to pay (a QR code for a method with a
+  link) and footer; it says "Re-created on" the `as_of` day, never the
+  day it was printed, and the filed issued copy is never replaced by it
+  (P4b S4.5).
 - `books.control_check { as_of? }` → `{ as_of, agrees, accounts: [{ role,
   code, name, balance, documents_total, unattached: [{ entry_id, line,
   date, amount }], difference, attention: [{ kind, id, status, total,