vxfw: add copy_to_clipboard command

Add a command to copy text to the clipboard via OSC 52

src/vxfw/App.zig

@@ -195,6 +195,14 @@ fn handleCommand(self: *App, cmds: *vxfw.CommandList) Allocator.Error!void {
             .tick => |tick| try self.addTick(tick),
             .set_mouse_shape => |shape| self.vx.setMouseShape(shape),
             .request_focus => |widget| self.wants_focus = widget,
+            .copy_to_clipboard => |content| {
+                self.vx.copyToSystemClipboard(self.tty.anyWriter(), content, self.allocator) catch |err| {
+                    switch (err) {
+                        error.OutOfMemory => return Allocator.Error.OutOfMemory,
+                        else => std.log.err("copy error: {}", .{err}),
+                    }
+                };
+            },
         }
     }
 }

src/vxfw/vxfw.zig

@@ -74,6 +74,10 @@ pub const Command = union(enum) {
     set_mouse_shape: vaxis.Mouse.Shape,
     /// Request that this widget receives focus
     request_focus: Widget,
+
+    /// Try to copy the provided text to the host clipboard. Uses OSC 52. Silently fails if terminal
+    /// doesn't support OSC 52
+    copy_to_clipboard: []const u8,
 };
 
 pub const EventContext = struct {
@@ -118,6 +122,10 @@ pub const EventContext = struct {
     pub fn requestFocus(self: *EventContext, widget: Widget) Allocator.Error!void {
         try self.addCmd(.{ .request_focus = widget });
     }
+
+    pub fn copyToClipboard(self: *EventContext, content: []const u8) Allocator.Error!void {
+        try self.addCmd(.{ .copy_to_clipboard = content });
+    }
 };
 
 pub const DrawContext = struct {