feat: complete FreeCAD BMU assembly (76 real components, 4.6MB GLB)

- Exported from BMU.FCStd via amrit3701/freecad-cli Docker container
- 686 objects in FCStd, 76 Part::Feature exported (real geometry only)
- Full assembly: BMU v2 board + switch MOSFET + I2C repeater + all SMD components
- Components: D2PAK MOSFETs, SOT-23, R_0603, capacitors, connectors, inductors
- Replaces separate bmu-v2-full.glb + bmu-switch-mosfet.glb
- SwitchBoard component removed (included in assembly)
- Hero HTML removed — PCB 3D is the full-page hero

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

src/components/WebGLBackground.tsx

@@ -30,14 +30,14 @@ let scrollProgress = 0;
 /* ---------- Real PCB Board (full 3D with components from FreeCAD) ---------- */
 function RealPCB() {
   let glb: any = null;
-  try { glb = useGLTF('/assets/models3d/bmu-v2-full.glb'); } catch {}
+  try { glb = useGLTF('/assets/models3d/bmu-assembly.glb'); } catch {}
 
   if (!glb?.scene) return null;
 
   return (
     <primitive
       object={glb.scene.clone()}
-      scale={120}
+      scale={0.15}
       rotation={[-Math.PI / 2, 0, 0]}
       position={[0, 0, 0]}
     />
@@ -458,7 +458,6 @@ function PCBScene() {
     <group>
       <Suspense fallback={null}>
         <RealPCB />
-        <SwitchBoard />
         <ComponentCluster />
       </Suspense>
       <CurrentFlow />
@@ -523,8 +522,7 @@ export default function WebGLBackground() {
 }
 
 /* Preload all models */
-useGLTF.preload('/assets/models3d/bmu-v2-full.glb');
-useGLTF.preload('/assets/models3d/bmu-switch-mosfet.glb');
+useGLTF.preload('/assets/models3d/bmu-assembly.glb');
 useGLTF.preload('/assets/models3d/resistor_0603.glb');
 useGLTF.preload('/assets/models3d/capacitor_0805.glb');
 useGLTF.preload('/assets/models3d/inductor_0805.glb');