* Upgrade ExtendedCache with support for named caches
* Addressed Claude PR suggestions - defensive mux creation, defend empty cache name, added tests
* Addressed PR suggestions; Fixed issue where IDistributedCache was missing when using the shared route; Added more unit tests
* Revert to TryAdd, document expectation that AddDistributedCache is called first
* Add FusionCache to service collection
* Refactored to it's own service collection extension, added full unit tests, added TryAdd style support
* Move to ExtendedCache instead of FusionCache, re-use exsting DistributedCache if present, expose backplane to DI
* Reworked builders to reuse multiplexer if present
