books.renumber_account: give an account a new code, history kept

Ledger::renumber_account changes only the code (entries name accounts by
id): refuses an unknown account, a blank or used code, and a control code
for an account of the wrong type or a placeholder. Journaled as
account.renumbered (with the previous code), replayed, projected, shown
in the viewer's journal. The MCP tool lists wanderbooks.toml settings
that still name the old code. The server instructions now warn that the
engine can't tell a same-type account with another purpose at a control
code (a hosting expense at payroll's 6100).

Tests: core property (only the code changes; trial balance equal), core
refusals, the store's command property, MCP end to end with restart.
Mutation on the new code: 8 of 8 viable caught.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01GWVo7x3UHw5kwCUaWxiejX

crates/ledger-store/tests/store.rs

@@ -952,6 +952,7 @@ mod refusals {
         SetEntryVendor(u64, Option<u64>),
         SetVendor1099(u64, bool),
         SetAccountTax(u64, u8),
+        Renumber(u64, u8),
         // The rest of the command surface (2026-10-13).
         AttachReceipt(Option<u64>, u8),
         FileDocument(u8),
@@ -1025,6 +1026,7 @@ mod refusals {
             (id.clone(), prop::option::of(0u64..4)).prop_map(|(e, v)| Op::SetEntryVendor(e, v)),
             (0u64..4, any::<bool>()).prop_map(|(v, t)| Op::SetVendor1099(v, t)),
             (0u64..10, 0u8..4).prop_map(|(a, k)| Op::SetAccountTax(a, k)),
+            (0u64..10, 0u8..9).prop_map(|(a, c)| Op::Renumber(a, c)),
             (prop::option::of(id.clone()), 0u8..4).prop_map(|(e, b)| Op::AttachReceipt(e, b)),
             (0u8..4).prop_map(Op::FileDocument),
             (0u64..6, id.clone()).prop_map(|(a, e)| Op::LinkReceipt(a, e)),
@@ -1143,6 +1145,14 @@ mod refusals {
             Op::SetEntryVendor(e, v) => store.set_entry_vendor(e, v),
             Op::SetVendor1099(v, t) => store.set_vendor_1099(v, Some(Form1099::Nec), t),
             Op::SetAccountTax(a, k) => store.set_account_tax(a, TAX[k as usize], None),
+            // The chart's codes, control codes (payroll's 6100 and 2110,
+            // revenue, receivables), a blank, and fresh ones.
+            Op::Renumber(a, c) => store.renumber_account(
+                a,
+                [
+                    "1000", "6100", "2110", "4000", "1200", "", "7001", "7002", "3999",
+                ][c as usize],
+            ),
             Op::AttachReceipt(e, b) => store
                 .attach_receipt(e, "r.pdf", "application/pdf", &[b; 3], Some("receipt"))
                 .map(drop),