better-route: replay-cache idempotency

Use IdempotencyMiddleware when replaying a completed response is useful but simultaneous duplicate execution is acceptable or impossible at another layer. It checks the store, invokes the handler, and stores only after completion; it does not reserve first.

For payments, order creation, subscriptions, account provisioning, or any irreversible side effect, use br-atomic-idempotency instead.

Production setup

use BetterRoute\Middleware\Write\IdempotencyMiddleware;
use BetterRoute\Middleware\Write\WpdbIdempotencyStore;

register_activation_hook(__FILE__, static function (): void {
    (new WpdbIdempotencyStore())->installSchema();
});