fix: resolve all DaisyUI audit issues

- settings.js: replace broken CSS vars with getThemeColor() helper
- base.html: add bg-primary text-primary-content active state to drawer
- All templates: btn-small -> btn-sm (DaisyUI standard)
- Delete orphan templates/components/header.html
- auth-utils.js: fix .show class -> use hidden (Tailwind)
- login.html: remove redundant auth-* classes, keep DaisyUI only
- auth-ui.js: update form selector for cleanup
- watchlist.html: fix nav active class styling
- 4 JS files (series-search, tabs, recommendations, anime-details):
  - Replace all old CSS classes with DaisyUI/Tailwind
  - Remove hardcoded colors, use theme-aware classes
  - loading-spinner -> DaisyUI loading component
  - no-results/search-results -> Tailwind utility layout
  - All badges -> DaisyUI badge variants

static/js/auth-utils.js

@@ -67,12 +67,12 @@ function displayError(elementId, error, defaultMessage = 'Une erreur est survenu
   }
 
   errorDiv.textContent = message;
-  errorDiv.classList.add('show');
-  
+  errorDiv.classList.remove('hidden');
+
   // Hide success message if visible
   const successDiv = document.getElementById(elementId.replace('Error', 'Success'));
   if (successDiv) {
-    successDiv.classList.remove('show');
+    successDiv.classList.add('hidden');
   }
 }
 
@@ -89,12 +89,12 @@ function displaySuccess(elementId, message) {
   }
 
   successDiv.textContent = message;
-  successDiv.classList.add('show');
-  
+  successDiv.classList.remove('hidden');
+
   // Hide error message if visible
   const errorDiv = document.getElementById(elementId.replace('Success', 'Error'));
   if (errorDiv) {
-    errorDiv.classList.remove('show');
+    errorDiv.classList.add('hidden');
   }
 }