Add server control (start/stop/restart, live logs, broadcast, kick) to webadmin

Docker SDK drives login/char/worldserver containers via docker.sock (mounted
read-only into webadmin); live logs stream over SSE with nginx buffering
disabled so lines arrive in real time. Broadcast/kick go through a new
admin_queue DB table that the world server polls every ~2s in its existing
WorldProcess tick loop, avoiding a second IPC channel to the game server.

webadmin/templates/base.html

@@ -71,6 +71,21 @@
   .badge.ok { background: #163a26; color: var(--ok); }
   .badge.off { background: #3a1620; color: var(--danger); }
   .row-actions a { margin-right: 8px; }
+  .logbox {
+    background: #0a0b10;
+    border: 1px solid var(--border);
+    border-radius: 8px;
+    padding: 12px;
+    height: 360px;
+    overflow-y: auto;
+    font-family: "SF Mono", Consolas, Menlo, monospace;
+    font-size: 12px;
+    white-space: pre-wrap;
+    word-break: break-all;
+  }
+  .service-tabs { display: flex; gap: 8px; margin-bottom: 12px; }
+  .service-tabs button.tab { background: #33384a; }
+  .service-tabs button.tab.active { background: var(--accent); }
 </style>
 </head>
 <body>
@@ -80,6 +95,7 @@
   <nav>
     <a href="{{ url_for('accounts') }}">Accounts</a>
     <a href="{{ url_for('characters') }}">Charaktere</a>
+    <a href="{{ url_for('server_control') }}">Server</a>
     <a href="{{ url_for('logout') }}">Logout ({{ session['username'] }})</a>
   </nav>
   {% endif %}