refactor: replace regex/preg_match with sscanf + ends_with in chunked upload

Two regex pieces in StoreChunkedAssetRequest, both replaced by more
fitting tools:

1. Parsing 'Content-Range' header — preg_match with capturing groups
   and $matches[1..3] indexing replaced by sscanf, which is
   purpose-built for parsing structured strings with a known format:

       $parsed = sscanf($header, 'bytes %d-%d/%d') ?: [];
       $start = $parsed[0] ?? null;

   No regex, no $matches array, no manual int casts (sscanf returns ints
   for %d).

2. Validating filename suffix — regex:/\.(jpe?g|png|gif|webp|mp4)$/i
   replaced by Laravel's built-in 'ends_with' rule, with extensions
   derived from the MediaType enum:

       $allowedSuffixes = collect([Image, Video])
           ->flatMap(fn (MediaType $t) => $t->extensions())
           ->map(fn ($ext) => '.'.$ext)
           ->all();

   For the case-insensitive part, normalize the filename to lowercase
   in prepareForValidation so 'IMG_1234.JPG' matches '.jpg' naturally.

Added MediaType::extensions() — single source of truth for filename
suffixes (jpg/jpeg/png/gif/webp + mp4/mov/webm). Mirrors
allowedMimeTypes() for callers that validate by name instead of MIME.

app/Enums/Media/Type.php

@@ -28,6 +28,21 @@ public function allowedMimeTypes(): array
         };
     }
 
+    /**
+     * Filename extensions that match this type. Used by callers that
+     * validate by name (chunked upload, URL fetch fallback) instead of
+     * by MIME.
+     *
+     * @return array<int, string>
+     */
+    public function extensions(): array
+    {
+        return match ($this) {
+            self::Image => ['jpg', 'jpeg', 'png', 'gif', 'webp'],
+            self::Video => ['mp4', 'mov', 'webm'],
+        };
+    }
+
     public function maxSizeInMb(): int
     {
         return (int) config("trypost.media.max_size_mb.{$this->value}");

app/Http/Requests/App/Asset/StoreChunkedAssetRequest.php

@@ -22,17 +22,15 @@ public function authorize(): bool
 
     protected function prepareForValidation(): void
     {
-        preg_match(
-            '/bytes (\d+)-(\d+)\/(\d+)/',
-            (string) $this->header('Content-Range'),
-            $matches,
-        );
+        $parsed = sscanf((string) $this->header('Content-Range'), 'bytes %d-%d/%d') ?: [];
 
         $this->merge([
-            'range_start' => isset($matches[1]) ? (int) $matches[1] : null,
-            'range_end' => isset($matches[2]) ? (int) $matches[2] : null,
-            'total_size' => isset($matches[3]) ? (int) $matches[3] : null,
-            'file_name' => $this->header('X-File-Name', 'upload'),
+            'range_start' => $parsed[0] ?? null,
+            'range_end' => $parsed[1] ?? null,
+            'total_size' => $parsed[2] ?? null,
+            // Lowercase the name so `ends_with` validation is effectively
+            // case-insensitive (IMG_1234.JPG vs img_1234.jpg).
+            'file_name' => strtolower((string) $this->header('X-File-Name', 'upload')),
         ]);
     }
 
@@ -41,11 +39,16 @@ protected function prepareForValidation(): void
      */
     public function rules(): array
     {
+        $allowedSuffixes = collect([MediaType::Image, MediaType::Video])
+            ->flatMap(fn (MediaType $type) => $type->extensions())
+            ->map(fn (string $ext) => '.'.$ext)
+            ->all();
+
         return [
             'range_start' => ['required', 'integer', 'min:0'],
             'range_end' => ['required', 'integer', 'gte:range_start'],
             'total_size' => ['required', 'integer', 'min:1', 'max:'.MediaType::Video->maxSizeInBytes()],
-            'file_name' => ['required', 'string', 'regex:/\.(jpe?g|png|gif|webp|mp4)$/i'],
+            'file_name' => ['required', 'string', 'ends_with:'.implode(',', $allowedSuffixes)],
         ];
     }
 
@@ -59,7 +62,7 @@ public function messages(): array
             'range_end.required' => 'Invalid Content-Range header',
             'total_size.required' => 'Invalid Content-Range header',
             'total_size.max' => 'File size exceeds the maximum allowed ('.MediaType::Video->maxSizeInMb().' MB).',
-            'file_name.regex' => 'File type not supported.',
+            'file_name.ends_with' => 'File type not supported.',
         ];
     }
 }