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/ui/sidebar/quick-connect-host.ts

@@ -1,6 +1,6 @@
 import type { SSHHostData } from "@/types";
 import type { Host } from "@/types/ui-types";
-import type { GuacamoleQuickHost } from "@/features/guacamole/GuacamoleApp";
+import type { GuacamoleQuickHost } from "../../../plugins/remote-desktop/frontend/GuacamoleApp";
 
 export type QuickConnectProtocol = "ssh" | "rdp" | "vnc";