sign SMAPI on install to avoid new macOS security restrictions

docs/release-notes.md

@@ -5,6 +5,7 @@
 * For players:
   * Updated mod compatibility list.
   * Fixed crash with some rare combinations of mods involving Harmony and mod APIs.
+  * Fixed compatibility with newer macOS security restrictions.
 
 * For mod authors:
   * Added `PathUtilities.CreateSlug` to turn an arbitrary string into a safe 'slug' that can be used in special contexts like URLs and file paths.  

src/SMAPI.Installer/InteractiveInstaller.cs

@@ -415,6 +415,21 @@ internal class InteractiveInstaller
                             }
                         }.Start();
                     }
+
+                    // sign SMAPI on macOS
+                    // This avoids 'StardewModdingAPI will damage your computer' errors in newer versions.
+                    if (context.Platform is Platform.Mac)
+                    {
+                        new Process
+                        {
+                            StartInfo = new ProcessStartInfo
+                            {
+                                FileName = "codesign",
+                                Arguments = $"--force --sign - \"{paths.UnixSmapiExecutablePath}\"",
+                                CreateNoWindow = true
+                            }
+                        }.Start();
+                    }
                 }
 
                 // copy the game's deps.json file