refactor: unify recipe routes into [recipeLang] slug with full bilingual support

Consolidate /rezepte and /recipes routes into single [recipeLang] structure to eliminate code duplication. All pages now use conditional API routing and reactive labels based on language parameter.

- Merge duplicate route structures into /[recipeLang] with 404 for invalid slugs
- Add English API endpoints for search, favorites, tags, and categories
- Implement language dropdown in header with localStorage persistence
- Convert all pages to use Svelte 5 runes (, , )
- Add German-only redirects (301) for add/edit pages
- Make all view pages (list, detail, filters, search, favorites) fully bilingual
- Remove floating language switcher in favor of header dropdown

.mcp.json.bak

@@ -0,0 +1,15 @@
+{
+	"mcpServers": {
+		"svelte": {
+			"type": "stdio",
+			"command": "npx",
+			"env": {
+				
+			},
+			"args": [
+				"-y",
+				"@sveltejs/mcp"
+			]
+		}
+	}
+}