refactor: integrate cache parameter into setDiscovery() method (#80)

* refactor: integrate cache parameter into setDiscovery() method

- Add cache as 4th parameter to setDiscovery()
- Rename $cache to $discoveryCache for clarity
- Remove separate setCache() method
- Update example to use new API

* docs: update discovery caching documentation to use new API

- Update examples to use cache parameter in setDiscovery() method
- Remove references to separate setCache() method calls

examples/09-cached-discovery-stdio/server.php

@@ -26,8 +26,7 @@ $server = Server::make()
     ->setServerInfo('Cached Discovery Calculator', '1.0.0', 'Calculator with cached discovery for better performance.')
     ->setContainer(container())
     ->setLogger(logger())
-    ->setDiscovery(__DIR__, ['.'])
-    ->setCache(new Psr16Cache(new ArrayAdapter()))
+    ->setDiscovery(__DIR__, ['.'], [], new Psr16Cache(new ArrayAdapter()))
     ->build();
 
 $transport = new StdioTransport(logger: logger());