merge: P4b S7, bad debts (branch S7, 4b4fecb9)

The fourth of the paused branches: Ledger::write_off and the bad_debts
control role, invoice.written_off with its evidence filed in the same
store call, books.write_off_invoice, the write-off on the timeline and
in Needs attention, Lean writeOff_within_bounds, rules.md B-41 and the
bookspec examples. Twenty-eight files conflicted with the S4.4, S5 and
S6 merges; resolved as plan 8.0.2 says, keeping both sides' appends with
their seams restored, and: the scope table at 125; S7's law numbered 37;
B-41 placed before B-42; the handbook's step 4 and recovery procedures
folded into the one invoices-and-bills section; S7's wire tests in their
own module with the confirm S4.4's contract needs; S7's copy of the
payment steps dropped (S6 replaced them with Ledger::settle) and its
write-off journaled through S6's journal_auto_lines; in the old-books
fixture S7's hand-written write-off moved to a second invoice, since
S6's hand-written payment settles invoice 1 in full.

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

crates/ledger-core/src/arap.rs

@@ -154,9 +154,10 @@ impl DocRef {
 }
 
 /// Why a ledger line carries its document: what it does to what is owed.
-/// Only `Origin` and `Payment` are written today (P4b S1); the rest are
-/// the movements later slices write (P4b.6), named here so a tag's kind
-/// never changes meaning.
+/// `Origin`, `Payment` and `WriteOff` are written today (S1, S7); the rest
+/// are movements only a later unit may write (P4b.6), named here so a
+/// tag's kind never changes meaning. `Adopted` and `RoleMove` are
+/// deferred (D-49).
 #[derive(Clone, Copy, Debug, PartialEq, Eq, PartialOrd, Ord, Hash, Serialize, Deserialize)]
 #[serde(rename_all = "snake_case")]
 pub enum Movement {
@@ -168,9 +169,9 @@ pub enum Movement {
     Discount,
     /// A bad debt written off (S7).
     WriteOff,
-    /// A legacy hand line adopted as the document (S7).
+    /// A legacy hand line adopted as the document (deferred, D-49).
     Adopted,
-    /// The balance moved with its control role (S7).
+    /// The balance moved with its control role (deferred, D-49).
     RoleMove,
 }