feat(files): add folder download as zip

- Add zip folder API endpoint
- Add download button to folder rows
- Enforce max archive size limit
- Document endpoint in OpenAPI

lib/agent/web/app.js

@@ -162,6 +162,15 @@
     return res.json();
   }
 
+  function downloadFolder(fullPath, folderName) {
+    const link = document.createElement("a");
+    link.href = `/api/v1/files/zip?path=${encodeURIComponent(fullPath)}`;
+    link.download = `${folderName}.zip`;
+    document.body.append(link);
+    link.click();
+    link.remove();
+  }
+
   async function deleteFile(fullPath, name) {
     if (!confirm(`Delete ${name}?`)) {
       return;
@@ -184,21 +193,37 @@
     for (const entry of entries) {
       const tr = document.createElement("tr");
       const name = document.createElement("td");
-      name.className = entry.type === "dir" ? "name" : "name file";
-      name.textContent = entry.name;
-      name.addEventListener("click", () => {
-        const full = joinPath(data.path, entry.name);
-        if (entry.type === "dir") {
+      const full = joinPath(data.path, entry.name);
+      if (entry.type === "dir") {
+        name.className = "name dir";
+        const label = document.createElement("span");
+        label.className = "dir-label";
+        label.textContent = entry.name;
+        label.addEventListener("click", () => {
           listFiles(full).catch((err) => showError(err.message));
-        } else {
+        });
+        const zipBtn = document.createElement("button");
+        zipBtn.type = "button";
+        zipBtn.className = "folder-zip";
+        zipBtn.textContent = "Download";
+        zipBtn.title = "Download folder as zip";
+        zipBtn.addEventListener("click", (event) => {
+          event.stopPropagation();
+          downloadFolder(full, entry.name);
+        });
+        name.append(label, zipBtn);
+      } else {
+        name.className = "name file";
+        name.textContent = entry.name;
+        name.addEventListener("click", () => {
           const link = document.createElement("a");
           link.href = `/api/v1/download?path=${encodeURIComponent(full)}`;
           link.download = entry.name;
           document.body.append(link);
           link.click();
           link.remove();
-        }
-      });
+        });
+      }
       const type = document.createElement("td");
       type.textContent = entry.type;
       const size = document.createElement("td");
@@ -207,7 +232,6 @@
       modified.textContent = entry.modified_time ? new Date(entry.modified_time).toLocaleString() : "";
       const action = document.createElement("td");
       action.className = "actions";
-      const full = joinPath(data.path, entry.name);
       const del = document.createElement("button");
       del.type = "button";
       del.className = "danger";

lib/agent/web/index.html

@@ -543,6 +543,20 @@
     tbody tr:hover td { background: rgba(94, 234, 212, 0.04); }
     tbody tr:last-child td { border-bottom: 0; }
     td.name { cursor: pointer; color: var(--accent); font-weight: 500; }
+    td.name.dir { display: flex; align-items: center; gap: 0.5rem; }
+    td.name .dir-label { flex: 1; min-width: 0; }
+    td.name .folder-zip {
+      flex-shrink: 0;
+      padding: 0.15rem 0.45rem;
+      font-size: 0.72rem;
+      font-weight: 500;
+      color: var(--text-muted);
+      background: var(--surface-2);
+      border: 1px solid var(--border);
+      border-radius: 4px;
+      cursor: pointer;
+    }
+    td.name .folder-zip:hover { color: var(--accent-bright); border-color: var(--accent-dim); }
     td.name.file { color: var(--text); font-weight: 400; }
     td.name.file:hover { color: var(--accent-bright); }
     td.actions { white-space: nowrap; text-align: right; }