fix: remove trailing comma in share text when there is no streak

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

src/lib/utils/share.ts

@@ -78,7 +78,7 @@ export function generateShareText(params: {
 
 	const lines = [
 		`${bookEmoji} Bibdle | ${formattedDate} ${bookEmoji}`,
-		`${guesses.length} ${guessWord},${streakPart}`,
+		`${guesses.length} ${guessWord}${streakPart ? `,${streakPart}` : ""}`,
 		`${emojis}${chapterStar}`
 	];