Add unique IP count and duplicate detection to sites page

The sites page previously showed total IP count which included duplicates
across multiple sites, leading to inflated numbers. Now displays unique
IP count as the primary metric with duplicate count shown when present.

- Add get_global_ip_stats() method to SiteService for unique/duplicate counts
- Update /api/sites?all=true endpoint to include IP statistics
- Update sites.html to display unique IPs with optional duplicate indicator
- Update API documentation with new response fields

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

app/web/templates/sites.html

@@ -26,8 +26,11 @@
     </div>
     <div class="col-md-4">
         <div class="stat-card">
-            <div class="stat-value" id="total-ips">-</div>
-            <div class="stat-label">Total IPs</div>
+            <div class="stat-value" id="unique-ips">-</div>
+            <div class="stat-label">Unique IPs</div>
+            <div class="stat-sublabel" id="duplicate-ips-label" style="display: none; font-size: 0.75rem; color: #fbbf24;">
+                (<span id="duplicate-ips">0</span> duplicates)
+            </div>
         </div>
     </div>
     <div class="col-md-4">
@@ -499,7 +502,7 @@ async function loadSites() {
         const data = await response.json();
         sitesData = data.sites || [];
 
-        updateStats();
+        updateStats(data.unique_ips, data.duplicate_ips);
         renderSites(sitesData);
 
         document.getElementById('sites-loading').style.display = 'none';
@@ -514,12 +517,20 @@ async function loadSites() {
 }
 
 // Update summary stats
-function updateStats() {
+function updateStats(uniqueIps, duplicateIps) {
     const totalSites = sitesData.length;
-    const totalIps = sitesData.reduce((sum, site) => sum + (site.ip_count || 0), 0);
 
     document.getElementById('total-sites').textContent = totalSites;
-    document.getElementById('total-ips').textContent = totalIps;
+    document.getElementById('unique-ips').textContent = uniqueIps || 0;
+
+    // Show duplicate count if there are any
+    if (duplicateIps && duplicateIps > 0) {
+        document.getElementById('duplicate-ips').textContent = duplicateIps;
+        document.getElementById('duplicate-ips-label').style.display = 'block';
+    } else {
+        document.getElementById('duplicate-ips-label').style.display = 'none';
+    }
+
     document.getElementById('sites-in-use').textContent = '-'; // Will be updated async
 
     // Count sites in use (async)