feat(share): update share rank caption and add URL

Share sheet now pre-fills:
"I'm a BRONZE Explorer on Eventify Plus! 7 EP earned.
Let's connect on the platform for more.

https://app.eventifyplus.com"

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

lib/features/share/share_rank_card.dart

@@ -58,7 +58,8 @@ class _ShareRankCardState extends State<ShareRankCard> {
 
       await Share.shareXFiles(
         [XFile(file.path)],
-        text: 'I\'m ranked #${widget.rank} on Eventify with ${widget.ep} EP! 🏆 #Eventify #Kerala',
+        subject: 'My Eventify Rank',
+        text: 'I\'m a ${widget.tier.toUpperCase()} Explorer on Eventify Plus! ${widget.ep} EP earned. Let\'s connect on the platform for more.\n\nhttps://app.eventifyplus.com',
       );
     } catch (e) {
       if (mounted) {