Add Share to X button with proper tweet text

- Added "Share to X" button next to "Copy link"
- Tweet text: "I made [song] game boy version. Click to listen or generate your own, made in Wario Synth by @b1rdmania"
- Updated Twitter cards to summary_large_image
- Dynamic OG description includes song title

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

index.html

@@ -1149,12 +1149,13 @@
                         </div>
                     </div>
 
-                    <div style="margin-top: 14px;">
-                        <button id="copyLinkBtn" type="button" disabled>Share</button>
-                        <div id="shareLinkBox" style="display: none; margin-top: 12px;">
-                            <input type="text" id="shareLinkInput" readonly style="width: 100%; font-size: 8px; padding: 10px;" />
-                            <div style="margin-top: 6px; font-size: 8px; color: var(--gb-dark);">Select and copy the link above</div>
-                        </div>
+                    <div style="margin-top: 14px; display: flex; gap: 12px; flex-wrap: wrap;">
+                        <button id="copyLinkBtn" type="button" disabled>Copy link</button>
+                        <button id="shareToXBtn" type="button" disabled>Share to X</button>
+                    </div>
+                    <div id="shareLinkBox" style="display: none; margin-top: 12px;">
+                        <input type="text" id="shareLinkInput" readonly style="width: 100%; font-size: 8px; padding: 10px;" />
+                        <div style="margin-top: 6px; font-size: 8px; color: var(--gb-dark);">Select and copy the link above</div>
                     </div>
                 </div>