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/portal-layout.js

@@ -0,0 +1,9 @@
+export {
+  panelPlacement,
+  SCHEMATIC_SLOTS,
+  SCHEMATIC_HEX_PATH,
+  SCHEMATIC_FLOOR_LINE,
+  SCHEMATIC_PANEL_LAYOUT,
+  PORTAL,
+  CELL,
+} from "./portal-geometry.js";