Manual @test, not part of regular suite. Run via --tests filter.

* feat(log): bridge JUL to SLF4J and improve shutdown log reliability

### What Changed
- gRPC now appear in the application log instead of going only to standard error.
- Database size stats are no longer printed at info level during startup, which reduces log noise.
- Shutdown now waits longer before stopping the log system, giving pending messages more time to flush.
- Async appender now allows up to 5 seconds to drain its queue on shutdown.
- Interrupted shutdowns now show a clearer log message.
- Test log config is INFO level.

### Impact
`✅ Fewer missed gRPC error logs`
`✅ Cleaner startup output`
`✅ Fewer lost shutdown logs`
`✅ Fewer test logs`

* docs(log): clarify resetJUL vs handler-removal responsibilities

* refactor(log): clean up TronLogShutdownHook constants, timing, and javadoc

* fix(log): fail fast on unreadable --log-config instead of silent fallback

* feat(log): slow signature verifications above 50ms

* feat(log): watchdog-warn when LevelDB open stalls

* test(log): pin TronLogShutdownHook wait-window semantics

* style(log): clarify LogService comment and tighten test local var casing

* refactor(log): drop manifest probe from LevelDB open watchdog

* feat(log): route grpc.* logs to dedicated grpc.log

* fix(log): make grpc logger asynchronous

* chore(log): register framework and plugin logger topics

* chore(log): raise slow signature verification to warn

* feat(proposal): add ALLOW_HARDEN_EXCHANGE_CALCULATION (code 98)

* fix(actuator): skip abstract classes in TransactionRegister

* feat(actuator,consensus): harden exchange transaction calculations (TIP-836)

Add SafeExchangeProcessor that replaces double arithmetic with
BigDecimal in the Bancor-formula calculation:

1. BigDecimal divide throws ArithmeticException on zero divisor
2. ExchangeCapsule.transaction() rejects negative post-trade balances
3. longValueExact() guards against BigDecimal-to-long saturation

Introduce AbstractExchangeActuator that overrides addExact/subtractExact
to route through allowHardenExchangeCalculation() flag, applied to all
four exchange actuators (Create, Inject, Transaction, Withdraw) for
consistent overflow detection.

ExchangeWithdrawActuator.validate() also gains a pure BigDecimal
precision-loss check when the proposal is active (previously used
double comparison).

Pre-activation behavior is byte-for-byte identical to legacy code.
Activation gated by ALLOW_HARDEN_EXCHANGE_CALCULATION (proposal 98).

* test(exchange): add hardened-path coverage for TIP-836

* feat(proposal): make ALLOW_HARDEN_EXCHANGE_CALCULATION togglable

* feat(actuator): wrap ArithmeticException in exchange actuators

* test: stabilize harden exchange proposal validation

…6658)

…ve (#6698)

* fix(consensus,framework,actuator): use Locale.ROOT for case-insensitive

String.toLowerCase()/toUpperCase() without an explicit Locale uses
Locale.getDefault(), which on Turkish (tr) or Azerbaijani (az) systems
folds 'I' to dotless-ı (U+0131) instead of 'i' (U+0069).
Changes:
- Fix all toLowerCase()/toUpperCase() calls to use Locale.ROOT
- Enable the ErrorProne StringCaseLocaleUsage checker at ERROR level
  to prevent future regressions at compile time
- Add one-time data migration (MigrateTurkishKeyHelper) to normalize
  all Turkish legacy keys (ı → i) at startup.

* refactor: consolidate Turkish key migration loops and use ASTHelpers

* test(toolkit): fix toLowerCase

* fix: use root locale in gradle case folding

* fix: gradle verification-metadata.xml

)

…6730)

…6726)

feat(vm): add P256VERIFY precompile (TIP-7951)