✨ Implement leadership-based permissions for Meetup management

- 🔒 Restrict event creation, editing, and deletion to Meetup leaders (`is_leader`) and creators for consistency across APIs, frontend, and MCP.
- ➕ Add new APIs for leader delegation: assign/remove Meetup leaders via `meetup_user.is_leader`.
- 🛠️ Replace loose member checks with specific leadership checks in policies, controllers, and views.
- 🧪 Add exhaustive tests to ensure only eligible leaders execute critical actions (e.g., event creation/edit, Meetup updates).
- 🔄 Refactor pivot relationships and models (`leadByMe`, `isLeader`) for explicit leadership handling.
- ✨ Introduce artisan command `meetups:promote-existing-leaders` to transition legacy data.

resources/views/livewire/meetups/index.blade.php

@@ -185,11 +185,10 @@ class extends Component {
 
                     <flux:table.cell>
                         <div class="flex flex-col space-y-2">
-                            @if(auth()->check() && $meetup->belongsToMe)
+                            @if(auth()->check() && $meetup->leadByMe)
                                 <div>
                                     <flux:button
-                                        :disabled="!$meetup->belongsToMe"
-                                        :href="$meetup->belongsToMe ? route_with_country('meetups.edit', ['meetup' => $meetup]) : null"
+                                        :href="route_with_country('meetups.edit', ['meetup' => $meetup])"
                                         size="xs"
                                         variant="filled" icon="pencil">
                                         {{ __('Bearbeiten') }}