Dreh-Speed Dropdown im Admin, Kalibrierungsversuch rückgängig gemacht

- Auto-Rotate Speed wählbar: 20-50% in 5er-Schritten (Standard 20%)
- BNO085 Magnetometer-Kalibrierung: calibration_status liefert immer 0,
  da der Sensor 3D-Bewegung benötigt die am Boden nicht möglich ist.
  Kalibrierungs-Feature vollständig entfernt.
- Empfehlung: Nord-Offset nach jedem Neustart neu setzen.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

gui/admin.html

@@ -189,6 +189,21 @@
               <span style="font-size:11px;color:#888;">° (0=N, 90=O, 180=S, 270=W)</span>
             </span>
           </div>
+          <div class="sr">
+            <span class="sr-led led-off"></span>
+            <span class="sr-key">Dreh-Speed</span>
+            <span class="sr-val">
+              <select id="rotate_speed" class="ctrl-select" style="font-size:11px;padding:2px 4px;">
+                <option value="20" selected>20 % (Standard)</option>
+                <option value="25">25 %</option>
+                <option value="30">30 %</option>
+                <option value="35">35 %</option>
+                <option value="40">40 %</option>
+                <option value="45">45 %</option>
+                <option value="50">50 %</option>
+              </select>
+            </span>
+          </div>
           <div class="act-grid">
             <button class="act-btn subtle full" id="rotate_start_btn" onclick="startRotate()">Zu Heading drehen</button>
             <button class="act-btn subtle full" id="rotate_stop_btn" onclick="stopRotate()" style="display:none;">Drehung abbrechen</button>
@@ -2946,14 +2961,16 @@
 
   async function startRotate() {
     var input = document.getElementById('rotate_target');
+    var speedEl = document.getElementById('rotate_speed');
     var target = parseFloat(input ? input.value : 0);
+    var speedPct = speedEl ? parseInt(speedEl.value) : 20;
     if (isNaN(target)) { alert('Ungültiger Winkel'); return; }
     setAdminStatus('Starte Drehung zu ' + target + '°…');
     try {
       var response = await fetch(adminApiBase + '/api/imu/rotate-to', {
         method: 'POST',
         headers: {'Content-Type': 'application/json'},
-        body: JSON.stringify({target_deg: target})
+        body: JSON.stringify({target_deg: target, speed_pct: speedPct})
       });
       var data = await response.json();
       if (!response.ok) throw new Error(data.status || ('status ' + response.status));