Deck builder: show prices in the Not owned card search

CardSearchBox gains a showPrice option that puts each result's price at
the right of its row; the deck builder's Not owned box turns it on.

Closes #21

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

src/styles.css

@@ -1375,6 +1375,12 @@ button.legality-tile-select {
 .result-list li:last-child {
   border-bottom: none;
 }
+.result-list .result-price {
+  margin-left: auto;
+  flex-shrink: 0;
+  font-variant-numeric: tabular-nums;
+  color: var(--text);
+}
 .result-list li:hover {
   background: var(--bg-hover);
 }