feat(dashboard): add share button with clipboard fallback

app/[lang]/dashboard/[planId]/_components/plan-dashboard.tsx

@@ -3,7 +3,7 @@
 import { useState, useEffect } from "react"
 import { format, eachDayOfInterval, isSameDay } from "date-fns"
 import { de, enUS } from "date-fns/locale"
-import { CalendarIcon, User, Home, X, Info, Utensils, Trash2, Check } from "lucide-react"
+import { CalendarIcon, User, Home, X, Info, Utensils, Trash2, Check, Share2 } from "lucide-react"
 import { toast } from "sonner"
 
 import { Button } from "@/components/ui/button"
@@ -220,6 +220,25 @@ export function PlanDashboard({ plan, dict, settingsDict, lang }: PlanDashboardP
                         dict={settingsDict}
                         lang={lang}
                     />
+                    <Button variant="outline" size="sm" onClick={() => {
+                        if (navigator.share) {
+                            navigator.share({
+                                title: plan.title,
+                                text: dict.shareTitle,
+                                url: window.location.href,
+                            }).catch(() => {
+                                // Fallback if share fails / is cancelled
+                                navigator.clipboard.writeText(window.location.href)
+                                toast.success(dict.copySuccess)
+                            })
+                        } else {
+                            navigator.clipboard.writeText(window.location.href)
+                            toast.success(dict.copySuccess)
+                        }
+                    }}>
+                        <Share2 className="w-4 h-4 mr-2" />
+                        {dict.share}
+                    </Button>
                 </div>
             </div>