row 113: admin DR verbs proven to land on the book's configured store (test-only; wiring landed in #556)

[MattJackson]

Row: /status 113 — admin DR verbs reach the configured store on predev; RefusingStore/StoreRef gone.

What. The wiring landed in #556 (5d279a5, 2026-10-07): boot binds the loader's adapter over the configured store onto the node's book (root/boot.rs verb_store: Some(adapter.verb_store())), main composes the admin units over that book (ProductionUnits::admin_over_book), and route hands units.store to busbar_core_admin::Verbs. The root's RefusingStore and StoreRef are deleted. This PR adds one test only: root/tests/kernel.rs the_admin_units_over_a_book_reach_that_books_store_for_every_recovery_verb.

Why. The booted cell from #556 (a_booted_nodes_recovery_verbs_reach_its_configured_store_through_the_book) goes RED when a verb is REFUSED. It stays green if the units hold a different store that also answers Ok. The new test puts a recording store on the book, composes the units through admin_over_book, drives chain_break, store_restore("nightly"), reseal_epoch_floor and the replay slot (commit, then read) through the units' handle, and asserts that each one, with its arguments, lands on THAT store in order. THE DESIGN: the store is reached through the loader adapter (busbar_contract::verb_store::Store). No new seam or ABI.

RED-able. Units with no store fail the expect. Units with any other store leave the recording log empty, so the assert_eq fails.

Ledgers touched: none. Test-only. 1.5.5 admin behaviour is unchanged.

Residual grep hit: git grep 'RefusingStore\|StoreRef' origin/predev -- crates now returns only a test-local fault double in busbar-a2a/src/a2a/tests/taskstore_tests.rs (a full-disk store for the a2a task registry, not related to admin). #787 deletes busbar-a2a, so this PR does not touch it (rule 4.2).

[MattJackson]

FYI (queue rule 20): $ draft #870 also edits crates/busbar/src/root/tests/kernel.rs (l.204-209, l.614-620: RawTierRates fixtures go through representable_nano_rate); disjoint from your l.408 block, merges clean.