feat (ui): voeg Volumes tabblad toe aan webui

Nieuw tabblad na Images met:
- Tabel: Naam, Driver, Mountpoint (afgekapt + tooltip), Aangemaakt
  (relatieve tijd), Labels (pills), Containers (pills via Mounts koppeling)
- Toolbar: Ververs, + Volume, Prune (met bevestigingsdialoog)
- Verwijder knop per rij (uitgeschakeld als volume in gebruik)
- Create Volume modal: naam (verplicht) + labels (key=value per regel)
- Lege staat via renderStateBox

volumes.js: _volEsc() voor XSS-safe rendering, encodeURIComponent
voor onclick-handlers, parallel fetch volumes + containers-dashboard
voor container-koppeling via Mounts[].Name.

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

webui/html/index.html

@@ -57,6 +57,9 @@
       <div class="tab" id="tab-images" onclick="setTab('images')" title="Images">
         <span class="navIcon">📦</span><span class="navLabel">Images</span><span class="navCount" id="countNavImages">-</span>
       </div>
+      <div class="tab" id="tab-volumes" onclick="setTab('volumes')" title="Volumes">
+        <span class="navIcon">🗄️</span><span class="navLabel">Volumes</span><span class="navCount" id="countNavVolumes">-</span>
+      </div>
       <div class="tab" id="tab-files" onclick="setTab('files')" title="Files">
         <span class="navIcon">📁</span><span class="navLabel">Files</span><span class="navCount" id="countNavFiles">-</span>
       </div>
@@ -305,6 +308,35 @@
     </div>
 </div>
 
+  <div id="view-volumes" class="grid" style="display:none">
+    <div class="card" style="grid-column: 1 / -1;">
+      <div class="cardHeader">
+        <div class="cardTitle">Volumes</div>
+        <div class="flex">
+          <button class="btn" onclick="loadVolumes()">Ververs</button>
+          <button class="btn ok" onclick="openCreateVolumeModal()">+ Volume</button>
+          <button class="btn bad" onclick="pruneVolumes()">Prune</button>
+        </div>
+      </div>
+      <div class="cardBody">
+        <table>
+          <thead>
+            <tr>
+              <th>Naam</th>
+              <th>Driver</th>
+              <th>Mountpoint</th>
+              <th>Aangemaakt</th>
+              <th>Labels</th>
+              <th>Containers</th>
+              <th style="width:90px;">Acties</th>
+            </tr>
+          </thead>
+          <tbody id="volumes-tbody"></tbody>
+        </table>
+      </div>
+    </div>
+  </div>
+
   <div id="view-files" class="grid" style="display:none">
     <div class="card" style="grid-column: 1 / -1;">
       <div class="cardHeader">
@@ -395,6 +427,30 @@
   </div>
 </div>
 
+<!-- Create Volume Modal -->
+<div class="modalBack" id="createVolumeModalBack" style="display:none;" onclick="closeCreateVolumeModal(event)">
+  <div class="modal" onclick="event.stopPropagation()" style="width:460px;">
+    <div class="modalHeader">
+      <div class="modalTitle">Volume aanmaken</div>
+      <button class="btn small ghost" onclick="hideCreateVolumeModal()">Sluiten</button>
+    </div>
+    <div class="modalBody">
+      <div style="margin-bottom:12px;">
+        <label class="label">Naam <span style="color:var(--bad)">*</span></label>
+        <input id="createVolumeName" class="input" type="text" placeholder="mijn-volume" style="width:100%;" />
+      </div>
+      <div style="margin-bottom:16px;">
+        <label class="label">Labels <span class="muted">(optioneel, één key=value per regel)</span></label>
+        <textarea id="createVolumeLabels" class="textarea mono" rows="3" placeholder="app=myapp&#10;env=production" style="width:100%;"></textarea>
+      </div>
+      <div class="flex">
+        <button class="btn ok" onclick="createVolume()">Aanmaken</button>
+        <button class="btn ghost" onclick="hideCreateVolumeModal()">Annuleren</button>
+      </div>
+    </div>
+  </div>
+</div>
+
 <!-- Build Modal -->
 <div class="modalBack" id="buildModalBack" style="display:none;" onclick="closeBuildModal(event)">
   <div class="modal" onclick="event.stopPropagation()" style="width:700px;">
@@ -590,6 +646,9 @@
     if (tab === "images") {
         loadImages();
     }
+    if (tab === "volumes") {
+        loadVolumes();
+    }
     // Start/stop live stats alleen in Containers tab (polling via /containers-dashboard)
     if (tab === 'containers') startContainersDashboardStatsPoll();
     else stopContainersDashboardStatsPoll();
@@ -772,5 +831,6 @@
 <script src="assets/js/d3.min.js"></script>
 <script src="assets/js/tabs/networks.js"></script>
 <script src="assets/js/tabs/images.js"></script>
+<script src="assets/js/tabs/volumes.js"></script>
 </body>
 </html>