Add per-application Docker image retention for rollback capability

Implement a per-application setting (`docker_images_to_keep`) in `application_settings` table to control how many Docker images are preserved during cleanup. The cleanup process now:

- Respects per-application retention settings (default: 2 images)
- Preserves the N most recent images per application for easy rollback
- Always deletes PR images and keeps the currently running image
- Dynamically excludes application images from general Docker image prune
- Cleans up non-Coolify unused images to prevent disk bloat

Fixes issues where cleanup would delete all images needed for rollback.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

app/Livewire/Project/Application/Rollback.php

@@ -4,6 +4,7 @@ namespace App\Livewire\Project\Application;
 
 use App\Models\Application;
 use Illuminate\Foundation\Auth\Access\AuthorizesRequests;
+use Livewire\Attributes\Validate;
 use Livewire\Component;
 use Visus\Cuid2\Cuid2;
 
@@ -19,9 +20,26 @@ class Rollback extends Component
 
     public array $parameters;
 
+    #[Validate(['integer', 'min:0', 'max:100'])]
+    public int $dockerImagesToKeep = 2;
+
     public function mount()
     {
         $this->parameters = get_route_parameters();
+        $this->dockerImagesToKeep = $this->application->settings->docker_images_to_keep ?? 2;
+    }
+
+    public function saveSettings()
+    {
+        try {
+            $this->authorize('update', $this->application);
+            $this->validate();
+            $this->application->settings->docker_images_to_keep = $this->dockerImagesToKeep;
+            $this->application->settings->save();
+            $this->dispatch('success', 'Settings saved.');
+        } catch (\Throwable $e) {
+            return handleError($e, $this);
+        }
     }
 
     public function rollbackImage($commit)
@@ -66,14 +84,12 @@ class Rollback extends Component
                     return str($item)->contains($image);
                 })->map(function ($item) {
                     $item = str($item)->explode('#');
-                    if ($item[1] === $this->current) {
-                        // $is_current = true;
-                    }
+                    $is_current = $item[1] === $this->current;
 
                     return [
                         'tag' => $item[1],
                         'created_at' => $item[2],
-                        'is_current' => $is_current ?? null,
+                        'is_current' => $is_current,
                     ];
                 })->toArray();
             }