feat(attachment): implement deletion of cropped attachments alongside original and update README

database/migrations/2026_08_18_000000_add_crop_data_to_attachments_table.php

@@ -13,6 +13,7 @@ return new class extends Migration
             $table->decimal('crop_vertical_start_percent', 7, 4)->nullable()->after('crop_horizontal_start_percent');
             $table->foreignId('cropped_attachment_id')
                 ->nullable()
+                ->unique()
                 ->after('crop_vertical_start_percent')
                 ->constrained('attachments')
                 ->nullOnDelete();