fix(picker): hide the Nano RP2040 Connect shell — art without a simulator

The metadata auto-scan sweeps every wokwi-elements board into the
registry, and boards Velxio does not emulate surface as component cards
that promise support we don't have. Filtered in the picker, not deleted
from the metadata: four saved projects already contain the element and
must keep rendering.

frontend/src/components/ComponentPickerModal.tsx

@@ -103,6 +103,15 @@ const BOARD_DESCRIPTIONS: Record<BoardKind, string> = {
   attiny85: '8-bit AVR, 8KB flash, 6 GPIO (browser)',
 };
 
+/**
+ * wokwi-elements ships art for boards Velxio does not emulate; the metadata
+ * auto-scan sweeps them into the registry as plain components. Listing one in
+ * the picker promises a board that will never boot, so they are hidden here —
+ * NOT deleted from components-metadata.json, because saved projects that
+ * already contain one still need the element to render.
+ */
+const UNSIMULATED_BOARD_SHELLS = new Set(['nano-rp2040-connect']);
+
 /**
  * Maker-first category order for the picker grid and the category filter.
  * Velxio's audience is hobbyist-heavy: everyday digital parts (sensors,
@@ -266,6 +275,12 @@ export const ComponentPickerModal: React.FC<ComponentPickerModalProps> = ({
     // (that is how "add a Pi 4" placed a 40-pin prop that never boots).
     components = components.filter((c) => !(c.id in BOARD_KIND_LABELS));
 
+    // wokwi-elements board shells with no simulator behind them. They come
+    // in through the metadata auto-scan and offering them reads as board
+    // support we don't have. Filtered here rather than removed from the
+    // metadata: saved projects that already placed one must keep rendering.
+    components = components.filter((c) => !UNSIMULATED_BOARD_SHELLS.has(c.id));
+
     // Maker-first ordering: most users reach for a sensor, an LED or a
     // display far more often than a bare transistor or a 74HC gate, so
     // passives / analog / logic sink to the end. Array.sort is stable —