Show friendly session status labels on the player dashboard

Players saw the raw enum value (e.g. "created") in the sessions
table, which doesn't mean anything to them. Adds SessionStatus::label()
mapping each status to a player-facing description like "Waiting for
players".

templates/game/dashboard.html.twig

@@ -67,7 +67,7 @@
                     <tr>
                         <td>{{ session.id }}</td>
                         <td>{{ session.game.name }}</td>
-                        <td><span class="badge bg-info text-dark">{{ session.status.value }}</span></td>
+                        <td><span class="badge bg-info text-dark">{{ session.status.label }}</span></td>
                         <td>{{ session.created|date('Y-m-d H:i') }}</td>
                         <td>
                             {% set inviteCode = '' %}