pc setup: hero falls back to the case present on the chosen day; add-ons (tilt pivot) are not counted as extra units in a slot card

src/lib/pc/SetupCard.svelte

@@ -10,6 +10,7 @@
 		slotIcon,
 		slotLabel,
 		thumb,
+		isAddOn,
 		units,
 		usageBadges,
 		type Part
@@ -34,7 +35,7 @@
 	} = $props();
 
 	const first = $derived(parts[0]);
-	const qty = $derived(parts.reduce((s, p) => s + units(p), 0));
+	const qty = $derived(parts.reduce((s, p) => s + (isAddOn(p) ? 0 : units(p)), 0));
 	const image = $derived(parts.flatMap((p) => p.imageUrls)[0] ?? null);
 	const names = $derived([...new Set(parts.map(displayName))]);
 	const spec = $derived(keySpec(first));

src/lib/pc/shared.ts

@@ -201,6 +201,9 @@ export const presentAt = (
 export type SlotCard = { key: string; slot: string; parts: Part[] };
 
 /** Visible parts of one section on day `at`, one card per slot (several parts may share it). */
+/** An add-on (e.g. a tilt pivot) extends another part in the same slot card; it is not counted as an extra unit. */
+export const isAddOn = (p: { model: string }) => /\badd-on\b/i.test(p.model);
+
 export function slotCards(parts: Part[], section: string, at: string): SlotCard[] {
 	const cards = new Map<string, SlotCard>();
 	for (const p of parts) {
@@ -216,8 +219,7 @@ export function slotCards(parts: Part[], section: string, at: string): SlotCard[
 		return i < 0 ? 999 : i;
 	};
 	// Add-ons (e.g. a monitor-arm tilt pivot) sit after the item they extend.
-	const addOn = (p: Part) => /\badd-on\b/i.test(p.model);
-	for (const c of cards.values()) c.parts.sort((a, b) => Number(addOn(a)) - Number(addOn(b)));
+	for (const c of cards.values()) c.parts.sort((a, b) => Number(isAddOn(a)) - Number(isAddOn(b)));
 	return [...cards.values()].sort((a, b) => rank(a.slot) - rank(b.slot));
 }