Add appcast.xml for updates only

appcast.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?>
+<rss version="2.0" xmlns:sparkle="http://www.andymatuschak.org/xml-namespaces/sparkle">
+    <channel>
+        <title>ShotScreen Updates</title>
+        <link>https://git.plet.i234.me/Nick/shotscreen/raw/branch/main/appcast.xml</link>
+        <description>ShotScreen Updates</description>
+        <language>en</language>
+        
+        <item>
+            <title>ShotScreen 1.0</title>
+            <description><![CDATA[
+                <h2>🎉 ShotScreen 1.0 - Initial Release</h2>
+                <p>The first official release of ShotScreen with full screenshot capabilities!</p>
+                <ul>
+                    <li>📸 Advanced screenshot capture modes</li>
+                    <li>🖱️ Intuitive user interface</li>
+                    <li>🔄 Automatic update system</li>
+                    <li>💾 Smart file management</li>
+                    <li>🎯 Multi-monitor support</li>
+                </ul>
+            ]]></description>
+            <pubDate>Fri, 28 Jun 2024 14:00:00 +0000</pubDate>
+            <enclosure url="https://git.plet.i234.me/Nick/shotscreen/releases/download/v1.0/ShotScreen-1.0.dmg"
+                       sparkle:version="1.0"
+                       sparkle:shortVersionString="1.0"
+                       length="11218106"
+                       type="application/octet-stream"
+                       sparkle:edSignature="mbPByOoTBLxvh7z/5Xmj8qd92ZQyT42e1KQhKfQimS2x174DsW5XyElrEQAvW5ps3W31jrcgOb5BfZ1rBItgBw==" />
+            <sparkle:minimumSystemVersion>13.0</sparkle:minimumSystemVersion>
+        </item>
+    </channel>
+</rss>