macos: export our ghostty surface ID type

macos/Ghostty-Info.plist

@@ -100,5 +100,20 @@
 	<false/>
 	<key>SUPublicEDKey</key>
 	<string>wsNcGf5hirwtdXMVnYoxRIX/SqZQLMOsYlD3q3imeok=</string>
+	<key>UTExportedTypeDeclarations</key>
+	<array>
+		<dict>
+			<key>UTTypeIdentifier</key>
+			<string>com.mitchellh.ghosttySurfaceId</string>
+			<key>UTTypeDescription</key>
+			<string>Ghostty Surface Identifier</string>
+			<key>UTTypeConformsTo</key>
+			<array>
+				<string>public.data</string>
+			</array>
+			<key>UTTypeTagSpecification</key>
+			<dict/>
+		</dict>
+	</array>
 </dict>
 </plist>