feat(recipes): give 'Bild entfernen' button persistent muted-red color

Was only red on hover — now always red at 60% opacity, full opacity on hover,
making the destructive intent immediately visible.

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

frontend/src/lib/recipes/RecipeForm.svelte

@@ -195,7 +195,7 @@
 					<button
 						type="button"
 						onclick={() => (heroImageUrl = null)}
-						class="mb-[8px] text-[12px] text-[var(--color-text-muted)] hover:text-[var(--color-error)] cursor-pointer"
+						class="mb-[8px] text-[12px] text-[var(--color-error)] opacity-60 hover:opacity-100 cursor-pointer"
 					>
 						Bild entfernen
 					</button>