feat: add a SurrealDB cache store driver

[ibourgeois]

Context

As a developer, I need Laravel cache operations to work against SurrealDB so local-first and graph-centric deployments can rely on a single persistence technology where appropriate.

Acceptance Criteria

• A cache store driver backed by SurrealDB is implemented.
• Core cache operations are covered by tests.
• Configuration for selecting the cache driver is documented.
• Any unsupported cache behaviors are documented explicitly.

Notes

This should integrate cleanly with Laravel's cache abstraction rather than bypassing it.

Out of Scope

• Session storage
• Queue storage

[ibourgeois]

Current note: this may now be partially or fully superseded by the broader Surreal Laravel driver work. Laravel's existing database cache path is now working on the Surreal connection and is covered by tests, so this issue may no longer require a separate custom cache-store driver implementation. We should revisit whether to close this as superseded or rewrite it to match the actual architecture.