feat(admin): add dashboard overview charts and log pagination

Enhance the admin panel by introducing visual overview charts for upload and storage trends, along with status bars for system metrics.

Additionally, implement pagination for the admin logs view, allowing users to navigate through log entries with configurable page sizes. Corresponding CSS styles have been added for the new charts, metrics grid, and pagination controls.

backend/templates/pages/admin.html

@@ -58,6 +58,55 @@
     </article>
   </div>
 
+  <div class="admin-charts">
+    <div class="card chart-card">
+      <div class="card-content">
+        <h2>Uploads per day</h2>
+        <p class="muted-copy">New boxes created over the last 14 days.</p>
+        <div class="bar-chart" role="img" aria-label="Uploads per day for the last 14 days">
+          {{range .Data.Overview.UploadDays}}
+          <div class="bar-chart-col" title="{{.Label}}: {{.Value}}">
+            <span class="bar-chart-value">{{.Value}}</span>
+            <span class="bar-chart-bar" style="height: {{.Height}}%"></span>
+            <span class="bar-chart-label">{{.Label}}</span>
+          </div>
+          {{end}}
+        </div>
+      </div>
+    </div>
+
+    <div class="card chart-card">
+      <div class="card-content">
+        <h2>Box status</h2>
+        <p class="muted-copy">Share of all {{.Data.Stats.TotalBoxes}} boxes.</p>
+        <div class="stat-bars">
+          {{range .Data.Overview.StatusBars}}
+          <div class="stat-bar">
+            <span>{{.Label}} <strong>{{.Value}}</strong></span>
+            <span class="stat-bar-track"><span class="stat-bar-fill" style="width: {{.Percent}}%"></span></span>
+          </div>
+          {{end}}
+        </div>
+      </div>
+    </div>
+  </div>
+
+  <div class="card chart-card">
+    <div class="card-content">
+      <h2>Storage added per day</h2>
+      <p class="muted-copy">Bytes uploaded over the last 14 days.</p>
+      <div class="bar-chart" role="img" aria-label="Storage added per day for the last 14 days">
+        {{range .Data.Overview.StorageDays}}
+        <div class="bar-chart-col" title="{{.Label}}: {{.Value}}">
+          <span class="bar-chart-value">{{.Value}}</span>
+          <span class="bar-chart-bar" style="height: {{.Height}}%"></span>
+          <span class="bar-chart-label">{{.Label}}</span>
+        </div>
+        {{end}}
+      </div>
+    </div>
+  </div>
+
   <div class="card admin-table-card">
     <div class="card-content">
       <div class="table-header">