feat: add i18n localization with language switcher to all web apps

- Add svelte-i18n configuration with SSR support to all web apps
- Create LanguageSelector component for each app with brand colors
- Add German and English locale files
- Integrate language switcher into login pages via headerControls snippet
- Fix Tailwind v4 @source directives for shared package scanning
- Update AppSlider styling to match login container design

Apps updated:
- Memoro (gold #f8d62b)
- Märchenzauber (pink #FF6B9D)
- ManaDeck (purple #8b5cf6)
- ManaCore (indigo #6366f1)

🤖 Generated with [Claude Code](https://claude.com/claude-code)

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

packages/shared-supabase/src/index.ts

@@ -37,6 +37,24 @@ export function createSupabaseAdminClient(config: SupabaseConfig): SupabaseClien
   });
 }
 
+/**
+ * Supabase error type
+ */
+export interface SupabaseError {
+  message: string;
+  code?: string;
+  details?: string;
+  hint?: string;
+}
+
+/**
+ * Standardized query result type
+ */
+export interface QueryResult<T> {
+  data: T | null;
+  error: SupabaseError | null;
+}
+
 /**
  * Common database query helpers
  */
@@ -44,16 +62,15 @@ export const dbHelpers = {
   /**
    * Handle Supabase query result and return standardized response
    */
-  handleQueryResult<T>(result: { data: T | null; error: any }): {
-    data: T | null;
-    error: { message: string; code?: string } | null;
-  } {
+  handleQueryResult<T>(result: { data: T | null; error: SupabaseError | null }): QueryResult<T> {
     if (result.error) {
       return {
         data: null,
         error: {
           message: result.error.message,
           code: result.error.code,
+          details: result.error.details,
+          hint: result.error.hint,
         },
       };
     }