Add disk-usage warnings and global health-check settings

- Setup wizard summary step: add disk-safety info box warning about
  health-check data accumulation and pointing to retention settings
- Setup wizard showSummary(): add dynamic disk-space tip with defaults
- Health Configure tab: add Global Settings section with data retention
  (default 30 days), polling interval (default 30s), and disk-usage
  warning threshold (default 80%), persisted to localStorage
- Rebuild dist bundles

status/js/setup-wizard.js

@@ -135,6 +135,22 @@ window.populateTimezoneSelect = function(selectEl, selectedTz) {
       </div>
     `;
 
+    // Disk-safety reminder (universal across all config types)
+    html += `
+      <div style="margin-top: 12px; padding: 12px 14px; border-radius: 8px; border: 1px solid var(--warn-fg, #f39c12); background: color-mix(in srgb, var(--warn-fg, #f39c12) 8%, transparent);">
+        <div style="display: flex; gap: 8px; align-items: flex-start;">
+          <span style="font-size: 1.1rem;">💾</span>
+          <div style="font-size: 0.85rem; line-height: 1.45;">
+            <strong style="color: var(--warn-fg, #f39c12);">Disk-space tip:</strong>
+            Health-check monitoring records uptime, response-time, and incident data continuously.
+            By default DashCaddy keeps <strong>30 days</strong> of history and warns at <strong>80% disk usage</strong>.
+            You can tune the retention period, polling interval, and disk threshold later under
+            <strong>Health → Configure → Global Settings</strong>.
+          </div>
+        </div>
+      </div>
+    `;
+
     html += '</div>';
     summaryContent.innerHTML = html;
     showStep('setup-step-summary');