fix(core,store): refuse control accounts of the wrong type, with a reason

Invoices, bills, payments, payroll, and closes post to accounts the
engine finds by code (1200, 2000, 4000, 6999, 3999, 6100-2150). If an
account with that code existed it was used whatever its type: a 1200
"Customer Deposits" liability would have taken receivables. Now
(the owner, 2026-10-13: never force an imported chart into our numbering)
the engine refuses with ControlAccountMismatch, naming the code, the
account, its type, the role, and the type needed, so the agent can work
it out with the human. A placeholder is refused too.

Every command checks all its control accounts before changing anything
(Ledger::check_controls, spec + SOURCE in its doc comment), so a refusal
never leaves a half-made account behind. One table of control accounts
(ledger_core::RECEIVABLES ... PAYROLL) replaces the codes duplicated
across the engine and the store.

Tests (spec-derived, all assert the books are untouched after the
refusal): an_invoice_refuses_a_1200_that_is_not_receivables,
an_invoice_refuses_a_placeholder_1200,
an_invoice_creates_nothing_when_its_second_account_is_wrong,
a_bill_refuses_a_2000_that_is_not_payables,
a_close_refuses_a_3999_that_is_not_equity.

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

crates/ledger-core/src/lib.rs

@@ -49,7 +49,10 @@ pub use classes::{Class, ClassId};
 pub use error::LedgerError;
 pub use form1099::{Form1099, Vendor1099Line, Vendor1099Report, vendor_1099_report};
 pub use journal::{EntryId, EntryStatus, JournalEntry, JournalLine};
-pub use ledger::{Ledger, ReconciliationReport, UnclearedLine};
+pub use ledger::{
+    ControlAccount, GENERAL_EXPENSES, Ledger, PAYABLES, PAYROLL, RECEIVABLES, RETAINED_EARNINGS,
+    REVENUE, ReconciliationReport, UnclearedLine,
+};
 pub use money::{Currency, Money};
 pub use payouts::{Payout, PayoutAdjustment, PayoutLine, PayoutTotals, payout_plan};
 pub use payroll::{PayrollLine, PayrollRun, PayrollRunId};