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/style.css

@@ -0,0 +1,20 @@
+:root {
+  color-scheme: dark;
+  --bg: #0a0c12;
+}
+
+* {
+  box-sizing: border-box;
+}
+
+html,
+body {
+  margin: 0;
+  height: 100%;
+  background: var(--bg);
+}
+
+portal-app {
+  display: block;
+  height: 100%;
+}