feat: implement programmatic SEO for solutions pages

- Add 10 oil-for-concern solution pages with localized slugs
- Support 4 languages: sr, en, de, fr with proper canonical URLs
- Add solutions hub, by-concern, and by-oil directory pages
- Filter bundle products from solutions pages
- Add hideLangSwitcher prop to Header component
- Update translations for all languages
- Fix canonical URLs to include locale prefix

src/i18n/messages/en.json

@@ -588,8 +588,10 @@
       "subtitle": "Explore our comprehensive collection of natural oil solutions, organized by skin concern to help you find exactly what you need.",
       "stats": {
         "availableConcerns": "{count} skin concerns covered",
-        "totalSolutions": "{count} expert-curated solutions"
+        "totalSolutions": "{count} expert-curated solutions",
+        "solutionsAvailable": "{count} solutions available"
       },
+      "viewSolution": "View Solution",
       "noResults": "No concerns found. Please check back later for new solutions."
     },
     "ByOil": {
@@ -601,6 +603,12 @@
         "availableOils": "{count} natural oils",
         "totalSolutions": "{count} expert-curated solutions"
       },
+      "oilCard": {
+        "solutionLabel": "solution available",
+        "solutionsLabel": "solutions available",
+        "bestFor": "Best for:",
+        "exploreSolutions": "Explore Oil Solutions"
+      },
       "noResults": "No oils found. Please check back later for new solutions."
     },
     "completeYourRoutine": "Complete Your Routine",