[wip] bugs to work out, but backend should support inventory

src/db/relations.ts

@@ -21,9 +21,21 @@ export const relations = defineRelations(schema, (r) => ({
         }),
         history: r.many.priceHistory(),
         latestSales: r.many.salesHistory(),
+        inventories: r.many.inventory(),
+    },
+    inventory: {
+        card: r.one.cards({
+            from: r.inventory.cardId,
+            to: r.cards.cardId,
+        }),
+        sku: r.one.skus({
+            from: [r.inventory.cardId, r.inventory.condition],
+            to: [r.skus.cardId, r.skus.condition],
+        }),
     },
     cards: {
         prices: r.many.skus(),
+        inventories: r.many.inventory(),
         set: r.one.sets({
             from: r.cards.setId,
             to: r.sets.setId,