fix(schedule): prevent duplicate SSL certificate regeneration

Run RegenerateSslCertJob on one server only and add coverage to ensure scheduled production jobs use onOneServer.

tests/Feature/ScheduleOnOneServerTest.php

@@ -0,0 +1,38 @@
+<?php
+
+use App\Models\InstanceSettings;
+use Illuminate\Console\Scheduling\Schedule;
+use Illuminate\Foundation\Testing\RefreshDatabase;
+
+uses(RefreshDatabase::class);
+
+beforeEach(function () {
+    InstanceSettings::unguarded(fn () => InstanceSettings::query()->firstOrCreate(['id' => 0]));
+});
+
+it('schedules RegenerateSslCertJob with onOneServer to prevent multi-server double dispatch', function () {
+    $schedule = app(Schedule::class);
+
+    $event = collect($schedule->events())->first(
+        fn ($e) => str_contains((string) $e->description, 'RegenerateSslCertJob')
+    );
+
+    expect($event)->not->toBeNull();
+    expect($event->onOneServer)->toBeTrue();
+});
+
+it('schedules every production job with onOneServer', function () {
+    $schedule = app(Schedule::class);
+
+    $jobEvents = collect($schedule->events())->filter(
+        fn ($e) => str_contains((string) $e->description, 'App\\Jobs\\')
+    );
+
+    expect($jobEvents)->not->toBeEmpty();
+
+    $jobEvents->each(function ($event) {
+        expect($event->onOneServer)->toBeTrue(
+            "Scheduled job [{$event->description}] is missing ->onOneServer()"
+        );
+    });
+});