refreshBentoBoxVaultHook() assumed BentoBox already held a VaultHook it
could re-hook. In the standalone case that is never true: BentoBox hooks
Vault during its early hooks, before addons enable, so when InvSwitcher
is the only economy that early hook fails for lack of any economy and is
discarded by HooksManager. getVault() then stays empty and the refresh
was a silent no-op, leaving Bank and the rest of BentoBox unable to see
our economy.

When getVault() is empty, register a fresh VaultHook now that our
provider is live, so getVault() is populated for economy consumers.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Admin eco give/set/take on an offline player reported a stale balance
(e.g. "New balance: 0.00" after giving 2000). The success message
re-read the balance from the database, which reloaded the offline player
fresh before the asynchronous save had flushed, returning the
pre-transaction value. Report the balance from the EconomyResponse the
transaction returned instead, which is authoritative.

Also harden the underlying offline read-after-write path: getStorageObject
loaded an independent transient copy for offline players on every call, so
two rapid sequential economy writes could each load before the first save
flushed, losing the first update. Track offline saves in flight in a
pending-saves map and reuse that object for follow-up reads/writes until
the last save flushes, then drop it so a later login still reloads fresh.
No main-thread blocking, no indefinite caching of offline players.

Add a regression test for the offline read-after-write path.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Main code:
- InvEconomy: drop redundant @deprecated from the Vault interface overrides
  (suppress the unavoidable deprecation/removal warnings at class level),
  extract duplicated debug literals into constants, and replace nested
  ternaries in debug routing with a routeSuffix() helper.
- Store: merge nested if in island-key migration; replace if/containsKey in
  getStat UNTYPED branch with Optional.ifPresent.
- Remove unused import in InvSwitcherPladdon.

Tests:
- Remove the 'public' modifier from JUnit 5 test classes and annotated
  methods (S5786).
- Add assertDoesNotThrow assertions to four clear-stored tests that had none.
- Remove redundant local Island mocks that shadowed the @mock field.
- Remove unused 'server' locals, unused imports, and unnecessary
  'throws Exception' declarations.

Left intentionally: S110 (command class depth is inherent to BentoBox's
CompositeCommand hierarchy), S3776 (cognitive complexity on core inventory
methods - refactoring risks regressions), and S5738 (calls to deprecated
Bukkit.getOfflinePlayer required to implement Vault's name-based methods).

All 124 tests pass.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>