feat: add web frontend for FabWorks API

Add static HTML/CSS/JS frontend with export browser, search, and
file download capabilities served via UseStaticFiles.

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

FabWorks.Api/wwwroot/js/helpers.js

@@ -0,0 +1,36 @@
+function fmtSize(b) {
+    if (!b) return '0 B';
+    const k = 1024, s = ['B','KB','MB','GB'];
+    const i = Math.floor(Math.log(b) / Math.log(k));
+    return parseFloat((b / Math.pow(k, i)).toFixed(1)) + ' ' + s[i];
+}
+
+function fmtDate(d) {
+    if (!d) return '';
+    const dt = new Date(d);
+    return dt.toLocaleDateString('en-US', { month: 'short', day: 'numeric', year: 'numeric' }) +
+        ' ' + dt.toLocaleTimeString([], { hour: '2-digit', minute: '2-digit' });
+}
+
+function fmtThickness(t) {
+    if (t == null) return '\u2014';
+    return `<span style="font-family:var(--font-mono)">${t.toFixed(4)}"</span>`;
+}
+
+function esc(s) {
+    return s ? s.replace(/</g,'&lt;').replace(/>/g,'&gt;').replace(/"/g,'&quot;').replace(/'/g,'&#39;') : '';
+}
+
+function setPage(title, tag = '') {
+    document.getElementById('page-title').textContent = title;
+    document.getElementById('page-tag').textContent = tag;
+    document.getElementById('page-tag').style.display = tag ? '' : 'none';
+}
+
+const api = {
+    async get(url) {
+        const r = await fetch(url);
+        if (!r.ok) throw new Error(`${r.status} ${r.statusText}`);
+        return r.json();
+    }
+};