✨ 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.

tests/Feature/Meetups/CreateMeetupEventSeriesTest.php

@@ -6,8 +6,8 @@ use App\Models\MeetupEvent;
 use Livewire\Livewire;
 
 it('creates a weekly series via the web editor using the shared action', function () {
-    actingAsUser();
-    $meetup = Meetup::factory()->create();
+    // Termin-Verwaltung erfordert Leaderschaft; Ersteller ist per Hook Leader.
+    $meetup = Meetup::factory()->create(['created_by' => actingAsUser()->id]);
 
     Livewire::test('meetups.create-edit-events', ['meetup' => $meetup])
         ->set('seriesMode', true)
@@ -22,15 +22,15 @@ it('creates a weekly series via the web editor using the shared action', functio
         ->assertHasNoErrors()
         ->assertRedirect();
 
-    // The web editor parses the end date at midnight, so the occurrence on the end
-    // date's evening falls outside the range: 2026-07-01, 07-08, 07-15, 07-22 = 4.
-    // The shared action yields the identical result for the same inputs.
-    expect(MeetupEvent::where('meetup_id', $meetup->id)->count())->toBe(4);
+    // Das Enddatum aus dem Datums-Picker gilt inklusiv bis zum Tagesende
+    // (endOfDay), daher ist das Vorkommen am Enddatum-Abend dabei:
+    // 2026-07-01, 07-08, 07-15, 07-22, 07-29 = 5. Deterministisch, unabhängig
+    // von der Laufzeit-Uhrzeit.
+    expect(MeetupEvent::where('meetup_id', $meetup->id)->count())->toBe(5);
 });
 
 it('previews the same dates it will create', function () {
-    actingAsUser();
-    $meetup = Meetup::factory()->create();
+    $meetup = Meetup::factory()->create(['created_by' => actingAsUser()->id]);
 
     Livewire::test('meetups.create-edit-events', ['meetup' => $meetup])
         ->set('seriesMode', true)
@@ -38,5 +38,5 @@ it('previews the same dates it will create', function () {
         ->set('startTime', '18:00')
         ->set('endDate', '2026-07-29')
         ->set('recurrenceType', RecurrenceType::Weekly->value)
-        ->assertSet('previewDates', fn ($dates) => count($dates) === 4);
+        ->assertSet('previewDates', fn ($dates) => count($dates) === 5);
 });