feat: implement Linux global hotkey support using X11 and XDG portal backends with integrated media controls.

internal/xhotkey/hotkey_linux_platform.go

@@ -0,0 +1,33 @@
+//go:build linux
+
+package hotkey
+
+import (
+	"context"
+	"sync"
+
+	"github.com/godbus/dbus/v5"
+)
+
+const (
+	linuxHKNone = iota
+	linuxHKX11
+	linuxHKPortal
+)
+
+type platformHotkey struct {
+	mu         sync.Mutex
+	registered bool
+	backend    int
+
+	// X11 (CGO)
+	ctx      context.Context
+	cancel   context.CancelFunc
+	canceled chan struct{}
+
+	// Wayland / XDG portal global shortcuts
+	portalStop  chan struct{}
+	portalDone  chan struct{}
+	portalConn  *dbus.Conn
+	sessionPath dbus.ObjectPath
+}