feat: improve accessibility and update color scheme based on PageSpeed insights

- Add aria-labels to icon-only links (add button, edit button, logo, nav toggle)
- Add main landmark element for better page structure
- Fix heading hierarchy on recipe pages (h1 → h2 → h3 progression)
- Add role="status" to loading placeholders to allow aria-label usage
- Update link colors from red to blue for better contrast in both light and dark modes
- Change hover colors from orange/red to light blue across all interactive elements
- Reduce font size of section labels (Season, Keywords) while maintaining semantic structure

These changes address PageSpeed accessibility recommendations including low-contrast text,
missing accessible names, prohibited ARIA attributes, missing landmarks, and improper
heading order.

src/lib/components/Card.svelte

@@ -190,7 +190,7 @@ const img_name = $derived(
 .tag:focus-visible
 {
 	transform: scale(1.04, 1.04);
-	background-color: var(--orange);
+	background-color: var(--nord8);
 	box-shadow: 0.2em 0.2em 0.2em 0.1em rgba(0, 0, 0, 0.3);
 }
 .tag:focus{