macos: honor fullscreen setting

macos/Sources/Features/Terminal/TerminalManager.swift

@@ -67,6 +67,11 @@ class TerminalManager {
             Self.lastCascadePoint = window.cascadeTopLeft(from: Self.lastCascadePoint)
         }
         
+        if (ghostty.windowFullscreen) {
+            // NOTE: this doesn't properly handle non-native fullscreen yet
+            c.window?.toggleFullScreen(nil)
+        }
+        
         c.showWindow(self)
     }
     

macos/Sources/Ghostty/AppState.swift

@@ -105,6 +105,15 @@ extension Ghostty {
             _ = ghostty_config_get(config, &v, key, UInt(key.count))
             return v
         }
+        
+        /// Whether to open new windows in fullscreen.
+        var windowFullscreen: Bool {
+            guard let config = self.config else { return true }
+            var v = false
+            let key = "fullscreen"
+            _ = ghostty_config_get(config, &v, key, UInt(key.count))
+            return v
+        }
 
         /// The background opacity.
         var backgroundOpacity: Double {

src/config/Config.zig

@@ -281,6 +281,10 @@ command: ?[]const u8 = null,
 /// Start new windows in fullscreen. This setting applies to new
 /// windows and does not apply to tabs, splits, etc. However, this
 /// setting will apply to all new windows, not just the first one.
+///
+/// On macOS, this always creates the window in native fullscreen.
+/// Non-native fullscreen is not currently supported with this
+/// setting.
 fullscreen: bool = false,
 
 /// The title Ghostty will use for the window. This will force the title