fix: unify theme system - fix theme switching persistence

- Unified localStorage key to 'theme-preference' across all components
- Fixed header.tsx using wrong localStorage key ('theme' instead of 'theme-preference')
- Added localStorage hybrid persistence for instant theme changes
- Removed router.refresh() which was causing stale data revert
- Replaced Blue theme with Sepia
- Consolidated auth() calls to prevent race conditions
- Updated UserSettingsData types to include all themes

keep-notes/components/providers-wrapper.tsx

@@ -0,0 +1,29 @@
+'use client'
+
+import { LanguageProvider } from '@/lib/i18n/LanguageProvider'
+import { LabelProvider } from '@/context/LabelContext'
+import { NotebooksProvider } from '@/context/notebooks-context'
+import { NotebookDragProvider } from '@/context/notebook-drag-context'
+import { NoteRefreshProvider } from '@/context/NoteRefreshContext'
+import type { ReactNode } from 'react'
+
+interface ProvidersWrapperProps {
+  children: ReactNode
+  initialLanguage?: string
+}
+
+export function ProvidersWrapper({ children, initialLanguage = 'en' }: ProvidersWrapperProps) {
+  return (
+    <NoteRefreshProvider>
+      <LabelProvider>
+        <NotebooksProvider>
+          <NotebookDragProvider>
+            <LanguageProvider initialLanguage={initialLanguage as any}>
+              {children}
+            </LanguageProvider>
+          </NotebookDragProvider>
+        </NotebooksProvider>
+      </LabelProvider>
+    </NoteRefreshProvider>
+  )
+}