✨(frontend) add phone number and pin display in info side panel

Create minimal UI to show telephony access details for testing SIP
functionality in staging deployment. Basic implementation for feature
validation.

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

@@ -213,6 +213,10 @@
         "ariaLabel": "Kopieer je vergaderadres",
         "copy": "Adres kopiëren",
         "copied": "Adres gekopieerd"
+      },
+      "phone": {
+        "call": "Bel:",
+        "pinCode": "Code:"
       }
     }
   },