Add scan concurrency and login delay sliders

Serialised logins now sleep `login_delay` seconds between each SSH
auth to prevent AD/LDAP lockout. Both max sessions (1-10) and login
delay (0-15s) are configurable via UI sliders in the header and
passed as JSON to all scan endpoints.

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

index.html

@@ -151,6 +151,44 @@ var Xr=function(e){if(!(this instanceof Xr))return new Xr(e);this.id="Thenable/1
     cursor: pointer;
   }
 
+  .scan-settings-wrap {
+    display: flex;
+    align-items: center;
+    gap: 8px;
+    background: var(--surface2);
+    border: 1px solid var(--border);
+    border-radius: 8px;
+    padding: 6px 12px;
+    font-size: 12px;
+    color: var(--text-dim);
+  }
+  .scan-settings-wrap input[type=range] {
+    -webkit-appearance: none;
+    width: 70px;
+    height: 4px;
+    background: var(--border);
+    border-radius: 2px;
+    outline: none;
+    cursor: pointer;
+  }
+  .scan-settings-wrap input[type=range]::-webkit-slider-thumb {
+    -webkit-appearance: none;
+    width: 13px; height: 13px;
+    border-radius: 50%;
+    background: var(--accent);
+    cursor: pointer;
+  }
+  .scan-settings-wrap .setting-val {
+    min-width: 22px;
+    color: var(--text);
+    font-weight: 600;
+  }
+  .scan-settings-sep {
+    width: 1px; height: 16px;
+    background: var(--border);
+    margin: 0 4px;
+  }
+
   .btn {
     display: flex;
     align-items: center;
@@ -424,6 +462,16 @@ var Xr=function(e){if(!(this instanceof Xr))return new Xr(e);this.id="Thenable/1
       </select>
     </div>
 
+    <div class="scan-settings-wrap">
+      <span>Sessions</span>
+      <input type="range" id="workersSlider" min="1" max="10" value="5" oninput="document.getElementById('workersVal').textContent=this.value">
+      <span class="setting-val" id="workersVal">5</span>
+      <div class="scan-settings-sep"></div>
+      <span>Login delay</span>
+      <input type="range" id="delaySlider" min="0" max="15" value="3" oninput="document.getElementById('delayVal').textContent=this.value+'s'">
+      <span class="setting-val" id="delayVal">3s</span>
+    </div>
+
     <button class="btn btn-primary" id="scanBtn" onclick="triggerScan()">
       <svg width="14" height="14" fill="none" stroke="currentColor" stroke-width="2.5" viewBox="0 0 24 24">
         <path d="M4 4v5h.582m15.356 2A8.001 8.001 0 004.582 9m0 0H9m11 11v-5h-.581m0 0a8.003 8.003 0 01-15.357-2m15.357 2H15"/>
@@ -810,16 +858,31 @@ async function clearAndRescan() {
   if (!confirm('This will delete all switch and link data, then run a full scan. Continue?')) return;
   const btn = document.getElementById('clearScanBtn');
   btn.disabled = true;
-  const res = await fetch('/api/scan/clear', { method: 'POST' });
+  const res = await fetch('/api/scan/clear', {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify(scanSettings()),
+  });
   if (res.status === 409) { alert('Scan already running'); btn.disabled = false; return; }
   startPolling();
 }
 
+function scanSettings() {
+  return {
+    workers:     parseInt(document.getElementById('workersSlider').value),
+    login_delay: parseInt(document.getElementById('delaySlider').value),
+  };
+}
+
 async function triggerScan(dept) {
   const url = dept === 'elec' ? '/api/scan/elec'
             : dept === 'gw'   ? '/api/scan/gw'
             : '/api/scan';
-  const res = await fetch(url, { method: 'POST' });
+  const res = await fetch(url, {
+    method: 'POST',
+    headers: { 'Content-Type': 'application/json' },
+    body: JSON.stringify(scanSettings()),
+  });
   if (res.status === 409) { alert('Scan already running'); return; }
   startPolling();
 }