fix: use json.Marshal for hx-vals in watchlist templates

web/components/watchlist/card_button.templ

@@ -1,6 +1,10 @@
 package watchlist
 
-import "fmt"
+import (
+	"fmt"
+
+	"mal/web/shared"
+)
 
 templ CardButton(
 	animeID int,
@@ -17,7 +21,14 @@ templ CardButton(
 			hx-delete={ string(templ.URL(fmt.Sprintf("/api/watchlist/%d?from=card", animeID))) }
 		} else {
 			hx-post="/api/watchlist/card"
-			hx-vals={ fmt.Sprintf(`{"anime_id": "%d", "anime_title": "%s", "anime_title_english": "%s", "anime_title_japanese": "%s", "anime_image": "%s", "airing": "%v"}`, animeID, title, titleEnglish, titleJapanese, imageURL, airing) }
+			hx-vals={ shared.HxVals(map[string]interface{}{
+				"anime_id": animeID,
+				"anime_title": title,
+				"anime_title_english": titleEnglish,
+				"anime_title_japanese": titleJapanese,
+				"anime_image": imageURL,
+				"airing": airing,
+			}) }
 		}
 		hx-target="this"
 		hx-swap="outerHTML"