Make the home page's AS name search work (closes #151)

The AS Name Search card on the home page said the search was coming
soon. It now asks the new GET /api/v1/search/as?q=<text>, which
searches the AS list built into asinfo, and lists the matches as links
to their AS pages. The answer holds the query, the number of matches
and the first 50 of them; an empty q answers 400. asinfo.Search now
ignores case, uses strings.Contains instead of its own substring loop,
and returns its matches in AS number order. A number, or AS and a
number, typed into the card still opens that AS's page. The card builds
the list with textContent, since the names come from outside data.

Model: opus-5-5

internal/templates/index.html

@@ -174,6 +174,38 @@
         #asname-results .search-message {
             font-size: 13px;
         }
+        #asname-results .error {
+            color: #c00;
+        }
+        .asname-list {
+            list-style: none;
+            margin: 12px 0 0 0;
+            padding: 0;
+            max-height: 400px;
+            overflow-y: auto;
+        }
+        .asname-list li {
+            border-bottom: 1px solid #eee;
+        }
+        .asname-list a {
+            display: block;
+            padding: 8px 4px;
+            color: #2c3e50;
+            text-decoration: none;
+            font-size: 14px;
+        }
+        .asname-list a:hover {
+            background: #f5f5f5;
+        }
+        .asname-list .asn {
+            font-weight: 600;
+            color: #3498db;
+        }
+        .asname-list .description {
+            display: block;
+            color: #7f8c8d;
+            font-size: 12px;
+        }
 
         /* IP Lookup result */
         .ip-result {
@@ -306,7 +338,7 @@
                     <input type="text" id="asname-input" placeholder="e.g., Google, Cloudflare" autocomplete="off">
                     <button type="submit">Search</button>
                 </form>
-                <p class="search-hint">Search for autonomous systems by organization name</p>
+                <p class="search-hint">Search for autonomous systems by organization name or handle</p>
                 <div id="asname-results"></div>
             </div>
 
@@ -387,24 +419,82 @@
             }
         });
 
-        // AS name search
+        // AS name search. The handles and descriptions come from outside data,
+        // so the results are built with textContent, never innerHTML.
+        const asNameResults = document.getElementById('asname-results');
+
+        // Replace the search results with one line of text.
+        function showASNameMessage(text, className) {
+            const line = document.createElement('p');
+            line.className = className;
+            line.textContent = text;
+            asNameResults.replaceChildren(line);
+        }
+
+        // List the matches of a search answer, each as a link to its AS page,
+        // and say how many more matched than the answer holds.
+        function showASNameMatches(data) {
+            if (data.total === 0) {
+                showASNameMessage('No AS matches "' + data.query + '".', 'search-message');
+                return;
+            }
+
+            const list = document.createElement('ul');
+            list.className = 'asname-list';
+            for (const match of data.results) {
+                const asn = document.createElement('span');
+                asn.className = 'asn';
+                asn.textContent = 'AS' + match.asn;
+
+                const description = document.createElement('span');
+                description.className = 'description';
+                description.textContent = match.description;
+
+                const link = document.createElement('a');
+                link.href = '/as/' + match.asn;
+                link.append(asn, ' ' + match.handle, description);
+
+                const item = document.createElement('li');
+                item.append(link);
+                list.append(item);
+            }
+            asNameResults.replaceChildren(list);
+
+            const more = data.total - data.results.length;
+            if (more > 0) {
+                const line = document.createElement('p');
+                line.className = 'search-message';
+                line.textContent = more.toLocaleString() + ' more matched. Narrow the search to see them.';
+                asNameResults.append(line);
+            }
+        }
+
         document.getElementById('asname-form').addEventListener('submit', function(e) {
             e.preventDefault();
             const query = document.getElementById('asname-input').value.trim();
             if (!query) return;
 
-            const resultsDiv = document.getElementById('asname-results');
-            resultsDiv.innerHTML = '<p class="loading">Searching...</p>';
-
-            // Use a simple client-side search against the asinfo data
-            // For now, redirect to AS page if it looks like an ASN
-            if (/^\d+$/.test(query)) {
-                window.location.href = '/as/' + query;
+            // A number, or AS and a number, opens that AS's page
+            const asn = query.replace(/^AS/i, '');
+            if (/^\d+$/.test(asn)) {
+                window.location.href = '/as/' + asn;
                 return;
             }
 
-            // Show a message that server-side search is coming
-            resultsDiv.innerHTML = '<p class="search-message">AS name search coming soon. For now, try an AS number.</p>';
+            showASNameMessage('Searching...', 'loading');
+
+            fetch('/api/v1/search/as?q=' + encodeURIComponent(query))
+                .then(response => response.json())
+                .then(response => {
+                    if (response.status === 'error') {
+                        showASNameMessage('Error: ' + response.error.msg, 'error');
+                    } else {
+                        showASNameMatches(response.data);
+                    }
+                })
+                .catch(error => {
+                    showASNameMessage('Error: ' + error.message, 'error');
+                });
         });
 
         // IP lookup