store: last mutation survivors killed; 98% with four equivalent left

Final store mutation run: 357 caught + 1 timeout of 365 viable (from 82%
this morning). Three of its seven survivors now have tests:
- replay refuses a re-chained journal whose schedule posting differs
  from what it re-derives (check_replayed_entry guards that event);
- a disposal refused for an account's type says the type it needed;
- a database whose last pages are damaged while its settings still read
  fails the integrity check and is rebuilt (verified to fail with the
  check disabled: "database disk image is malformed").
The four left are equivalent: sort_value's two arms, OpenFlags | vs ^,
and writing the long form of a sweepless retained-earnings close.

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

docs/testing.md

@@ -27,6 +27,7 @@ the store's journal safety; the other crates come next (gap list).
 | Golden | `tests/golden/fixture_company.json` (5) | `invariants.rs` | `just check` | <1s | every change |
 | Benchmarks | a baseline (6) | `ledger-core/benches/books.rs`, `ledger-store/benches/store.rs` | `just bench` | ~2 min | none (no budget, by decision) |
 | Mutation | can the tests fail? | `ledger-core` (2026-10-13: 1,011 caught + 13 timeouts of 1,024 viable, 0 missed) | `just mutants` | ~3 h | weekly |
+| Mutation (store) | can the tests fail? | `ledger-store` (2026-10-13: 357 caught + 1 timeout of 365 viable, from 82%; three of its seven survivors then killed; four equivalent left: `sort_value`'s two arms, `OpenFlags` `|` vs `^`, the long form of a sweepless close) | `just mutants-store` | ~12 min | weekly |
 
 CI: `.github/workflows/check.yml` runs `just check` on every push;
 `scheduled.yml` runs proofs, the oracle, fuzzing, and mutation weekly.