✨(frontend) add participant menu with pin/unpin and admin remove actions

Introduce participant menu in participant list to enable more
participant actions and interactions beyond current capabilities.

Initialize menu with universal pin/unpin track action available to all
users, plus admin-restricted participant removal action. Completes
admin action set by enabling room ejection functionality.

Menu designed for reuse when called from participant tile focus
components, providing consistent interaction patterns across different
contexts where participant management is needed.

src/frontend/src/locales/nl/rooms.json

@@ -456,6 +456,21 @@
         "label": "{{name}} weigeren voor de vergadering",
         "all": "Alles weigeren"
       }
+    },
+    "moreOptions": "Meer opties"
+  },
+  "participantMenu": {
+    "remove": {
+      "label": "Van het gesprek uitsluiten",
+      "ariaLabel": "{{name}} van het gesprek uitsluiten"
+    },
+    "unpin": {
+      "label": "Losmaken",
+      "ariaLabel": "Maak {{name}} los"
+    },
+    "pin": {
+      "label": "Pinnen",
+      "ariaLabel": "Maak {{name}} vast"
     }
   },
   "recordingStateToast": {