update readme and add icons

frontend/src/App.jsx

@@ -2130,6 +2130,24 @@ function Flow() {
     input.click();
   }, [applyWorkflowData]);
 
+  const uploadPlugin = useCallback(() => {
+    const input = document.createElement('input');
+    input.type = 'file';
+    input.accept = '.py';
+    input.onchange = async (e) => {
+      const file = e.target.files[0];
+      if (!file) return;
+      setStatus({ text: 'Uploading plugin…', level: 'info' });
+      try {
+        await api.uploadPlugin(file);
+        // Node list refresh is handled by the nodes_updated WebSocket message.
+      } catch (err) {
+        setStatus({ text: err.message, level: 'error' });
+      }
+    };
+    input.click();
+  }, []);
+
   // ── Drag-and-drop workflow image loading ───────────────────────────
 
   const onDropFile = useCallback(async (event) => {
@@ -2820,6 +2838,9 @@ function Flow() {
             <button className="btn" onClick={copySnapshot} title="Copy workflow screenshot to clipboard">
               ⎘ Snapshot
             </button>
+            <button className="btn" onClick={uploadPlugin} title="Upload a plugin (.py)">
+              ⊕ Plugin
+            </button>
           </div>
 
           <div className={`status-bar ${status.level}`}>{status.text}</div>

frontend/src/api.js

@@ -90,6 +90,20 @@ export async function uploadFile(file, { relativePath = '' } = {}) {
   return r.json();
 }
 
+export async function uploadPlugin(file) {
+  const fd = new FormData();
+  fd.append('file', file);
+  const r = await fetch('/upload-plugin', { method: 'POST', body: fd });
+  if (r.status === 404) {
+    throw new Error('Plugin upload is not available in this build.');
+  }
+  if (!r.ok) {
+    const text = await r.text();
+    throw new Error(text || `Upload failed (${r.status})`);
+  }
+  return r.json();
+}
+
 export async function getChannels(filepath) {
   const r = await sessionFetch(`/channels?file=${encodeURIComponent(filepath)}`);
   if (!r.ok) return [{ name: 'field', type: 'DATA_FIELD' }];