feat(backups): support scheduled backups for application storage targets

Add polymorphic volume backup scheduling for persistent volumes and directories, expose schedule management via API, and reorganize backup configuration and execution views.

resources/views/livewire/project/database/create-scheduled-backup.blade.php

@@ -2,19 +2,6 @@
     <x-forms.input placeholder="0 0 * * * or daily" id="frequency"
         helper="You can use every_minute, hourly, daily, weekly, monthly, yearly or a cron expression." label="Frequency"
         required />
-    <h2>S3</h2>
-    @if ($definedS3s->count() === 0)
-        <div class="text-red-500">No validated S3 Storages found.</div>
-    @else
-        <x-forms.checkbox wire:model.live="saveToS3" label="Save to S3" />
-        @if ($saveToS3)
-            <x-forms.select id="s3StorageId" label="Select a S3 Storage">
-                @foreach ($definedS3s as $s3)
-                    <option value="{{ $s3->id }}">{{ $s3->name }}</option>
-                @endforeach
-            </x-forms.select>
-        @endif
-    @endif
     <x-forms.button type="submit" @click="modalOpen=false">
         Save
     </x-forms.button>