Move request parsing into DTOs via fromRequest(), expand update handler

Each DTO now owns its own parsing logic via fromRequest(), removing
the normalization layer from MicropubRequest entirely. UpdateHandler
gains delete support and allows replace/add/delete to compose in a
single request rather than being mutually exclusive.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

app/Services/Micropub/Data/MicropubData.php

@@ -4,8 +4,12 @@ declare(strict_types=1);
 
 namespace App\Services\Micropub\Data;
 
+use Illuminate\Http\Request;
+
 abstract class MicropubData
 {
+    abstract public static function fromRequest(Request $request): static;
+
     abstract public static function fromArray(array $data): static;
 
     abstract public function toArray(): array;