fix: maximize instead of fullscreen

This fixes interactions with the window manager including dodging
exclusive zones, correctly sharpening corners when the window manager
sets the maximized mode, and correctly toggling the maximized state when
either F11 or the maximize button are clicked.

src/app/core.rs

@@ -27,7 +27,6 @@ pub struct Window {
     pub header_title: String,
     pub use_template: bool,
     pub content_container: bool,
-    pub can_fullscreen: bool,
     pub sharp_corners: bool,
     pub show_context: bool,
     pub show_headerbar: bool,
@@ -103,7 +102,6 @@ impl Default for Core {
                 header_title: String::new(),
                 use_template: true,
                 content_container: true,
-                can_fullscreen: false,
                 sharp_corners: false,
                 show_context: false,
                 show_headerbar: true,