feat: add STEP/STL download links to gallery cards, persist models from server

- Gallery cards now show STEP and STL download buttons
- Loading a gallery item updates the viewer download bar
- Gallery loads existing models from server on page load

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

web/index.html

@@ -1054,6 +1054,31 @@
     gap: 8px;
   }
 
+  .gallery-card-downloads {
+    display: flex;
+    gap: 6px;
+    margin-top: 4px;
+  }
+
+  .gallery-dl {
+    all: unset;
+    font-family: var(--font-mono);
+    font-size: 9px;
+    font-weight: 600;
+    padding: 3px 8px;
+    border: 1px solid var(--border);
+    border-radius: 3px;
+    color: var(--accent);
+    cursor: pointer;
+    text-decoration: none;
+    transition: all 0.15s;
+  }
+
+  .gallery-dl:hover {
+    background: var(--accent-glow);
+    border-color: var(--accent-dim);
+  }
+
   /* ---- ANIMATIONS ---- */
 
   @keyframes fade-in-up {
@@ -1842,15 +1867,21 @@ function renderGallery() {
 
   let html = '';
   for (const item of galleryItems) {
-    html += '<button class="gallery-card fade-in" onclick="loadGalleryItem(\'' + escapeHtml(item.name) + '\')">';
-    html += '<div class="gallery-card-name">' + escapeHtml(item.name) + '</div>';
+    const name = escapeHtml(item.name);
+    html += '<div class="gallery-card fade-in">';
+    html += '<div class="gallery-card-name" onclick="loadGalleryItem(\'' + name + '\')" style="cursor:pointer">' + name + '</div>';
     html += '<div class="gallery-card-meta">';
     if (item.faces) html += '<span>' + item.faces + ' faces</span>';
     if (item.machinable !== undefined) {
       html += '<span style="color:' + (item.machinable ? 'var(--success)' : 'var(--error)') + '">'
         + (item.machinable ? '\u2713 CNC' : '\u2717 CNC') + '</span>';
     }
-    html += '</div></button>';
+    html += '</div>';
+    html += '<div class="gallery-card-downloads">';
+    html += '<a class="gallery-dl" href="/api/models/' + name + '.step" download>STEP</a>';
+    html += '<a class="gallery-dl" href="/api/models/' + name + '.stl" download>STL</a>';
+    html += '</div>';
+    html += '</div>';
   }
 
   grid.innerHTML = html;
@@ -1861,6 +1892,8 @@ async function loadGalleryItem(name) {
   setViewerLoading(true, 'LOADING MODEL...');
   try {
     await loadSTL('/api/models/' + name + '.stl');
+    currentPartName = name;
+    updateDownloads(name);
   } catch (e) {
     console.warn('Failed to load:', e);
   }
@@ -1970,6 +2003,25 @@ document.addEventListener('keydown', (e) => {
   }
 });
 
+// ── LOAD SERVER MODELS INTO GALLERY ──────────────────
+
+async function loadServerModels() {
+  try {
+    const resp = await fetch('/api/models');
+    const data = await resp.json();
+    if (data.models && data.models.length > 0) {
+      const existingNames = new Set(galleryItems.map(i => i.name));
+      for (const model of data.models) {
+        if (!existingNames.has(model.name)) {
+          galleryItems.push({ name: model.name });
+        }
+      }
+    }
+  } catch (e) {
+    console.warn('Failed to load server models:', e);
+  }
+}
+
 // ── INIT ──────────────────────────────────────────────
 
 initViewer();
@@ -1977,6 +2029,7 @@ checkServer();
 setInterval(checkServer, 15000);
 
 loadState();
+loadServerModels();
 // Re-render restored messages
 if (chatHistory.length > 0) {
   const examples = document.getElementById('quick-examples');