✨ 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/ManageEventsAuthTest.php

@@ -0,0 +1,29 @@
+<?php
+
+use App\Models\Meetup;
+use App\Models\User;
+use Livewire\Livewire;
+
+it('lets a leader open the event editor', function () {
+    $meetup = Meetup::factory()->create(['created_by' => actingAsUser()->id]);
+
+    Livewire::test('meetups.create-edit-events', ['meetup' => $meetup])
+        ->assertOk();
+});
+
+it('blocks a non-leader member from the event editor', function () {
+    $member = actingAsUser();
+    $meetup = Meetup::factory()->create(['created_by' => User::factory()->create()->id]);
+    $meetup->addMember($member); // is_leader = false
+
+    Livewire::test('meetups.create-edit-events', ['meetup' => $meetup])
+        ->assertStatus(403);
+});
+
+it('blocks a stranger from the event editor', function () {
+    actingAsUser();
+    $meetup = Meetup::factory()->create(['created_by' => User::factory()->create()->id]);
+
+    Livewire::test('meetups.create-edit-events', ['meetup' => $meetup])
+        ->assertStatus(403);
+});