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/main-axios.ts

@@ -2191,13 +2191,13 @@ export {
 export type {
   GuacamoleTokenRequest,
   GuacamoleTokenResponse,
-} from "@/api/guacamole-api";
+} from "../../plugins/remote-desktop/frontend/guacamole-api";
 export {
   getGuacamoleDpi,
   getGuacamoleToken,
   getGuacamoleTokenFromHost,
   getGuacdStatus,
-} from "@/api/guacamole-api";
+} from "../../plugins/remote-desktop/frontend/guacamole-api";
 
 // ============================================================================
 // RBAC MANAGEMENT