feat: wire remote-desktop plugin into core and rename i18n keys

Repoints core consumers (dispatcher, collab, session-sharing, tab
utils) at the plugin, adds isTabTypeAvailable gating for rdp/vnc/
telnet, widens hostCapability to accept an array, and renames the
guacamole i18n namespace to remoteDesktop.

src/main.tsx

@@ -59,7 +59,7 @@ const DockerApp = lazy(() =>
   })),
 );
 const GuacamoleApp = lazy(() =>
-  import("@/features/guacamole/GuacamoleApp").then((m) => ({
+  import("../plugins/remote-desktop/frontend/GuacamoleApp").then((m) => ({
     default: m.default,
   })),
 );