SaaS: Option to refresh cache for individual roles

### User story

Currently, the option to update the cache -in the cloud (SaaS version of Shopware) - is reserved/limited for/to the admin role. There is no option to set individual additional permissions for a specific (non-admin) role.

This option is available in the on-premise version (see screenshot):

### Acceptance criteria

- There is a way to set a permission for a (non-admin) role that enables the role the option to refresh the cache

### Definition of Done

- [ ] Fulfills all acceptance criteria defined during discovery.
- [ ] Integration/E2E testing in staging is done.
- [ ] All integration/E2E/unit tests passing; all critical or high-priority bugs are resolved.
- [ ] Fulfills compliance, performance, security, and cloud-readiness needs.
- [ ] Observability—includes monitoring, alerting, and logging; incident response handbooks updated.
- [ ] Documentation—developer docs are written or updated, including information on how the feature or change is adopted and tested. If new functionality, end user documentation is written or updated.
- [ ] (conditional) All new API endpoints have a defined API schema.
- [ ] (conditional) If the change affects the Storefront, it has been tested in the latest three versions of Firefox, Chrome, Edge, IE11, and Safari, as well as the different viewports and devices (Desktop / Tablet / Mobile).
- [ ] (conditional) If the change affects the Administration, it has been tested in current versions of Firefox, Chrome, and Edge.
- [ ] (conditional) Functionality that includes new API routes are callable via the Store-API (/store-api/[version]/).
- [ ] (conditional) If a new Admin module is created, the access control layer is provided, and permissions can be managed via the Users & Permissions module.
- [ ] (conditional) If a new UI input field or interactive element is introduced, the ACL wrapper is added.
- [ ] (conditional) Performance testing done if the change has a high performance impact, such as affecting scalability, load balancing, or query optimization.

No files or tests are named. Start by locating the SaaS cache-refresh permission and comparing it with the existing on-premise role-permission behavior; done means a non-admin role can be granted permission to refresh the cache and the relevant integration, E2E, and unit tests pass.

Written by the indexing model from the issue text.