Add portal web simulator, SPI bridges, and Pico firmware updates.

Bring the five-panel hex portal online with a browser 3D/schematic preview, Pi SPI backends, and renamed multi-panel Pico UDP firmware.

Co-authored-by: Cursor <cursoragent@cursor.com>

web/js/dev-reload.js

@@ -0,0 +1,17 @@
+/** Live reload when web/ files change (dev server only). */
+
+function connect() {
+  const source = new EventSource("/api/dev/reload");
+  source.onmessage = (event) => {
+    if (event.data === "reload") {
+      console.log("[portal] reloading…");
+      location.reload();
+    }
+  };
+  source.onerror = () => {
+    source.close();
+    setTimeout(connect, 1500);
+  };
+}
+
+connect();