Fix Next.js 15 compatibility and TypeScript errors

- Update API route handlers to use async params for Next.js 15 compatibility
- Fix MUI DataGrid deprecated props (pageSize -> initialState.pagination)
- Replace Material-UI Grid components with Box for better compatibility
- Fix admin authentication system with proper request parameters
- Update permission constants to match available AdminPermission enum values
- Add missing properties to Page interface for type safety
- Update .gitignore to exclude venv/, import logs, and large data directories
- Optimize Next.js config to reduce memory usage during builds

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

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

app/[locale]/pages/[slug]/page.tsx

@@ -30,10 +30,10 @@ interface PageData {
 }
 
 interface PageProps {
-  params: {
+  params: Promise<{
     locale: string
     slug: string
-  }
+  }>
 }
 
 async function getPageData(slug: string): Promise<PageData | null> {
@@ -55,7 +55,8 @@ async function getPageData(slug: string): Promise<PageData | null> {
 }
 
 export async function generateMetadata({ params }: PageProps): Promise<Metadata> {
-  const page = await getPageData(params.slug)
+  const resolvedParams = await params
+  const page = await getPageData(resolvedParams.slug)
 
   if (!page) {
     return {
@@ -184,14 +185,15 @@ function renderContent(content: string, contentType: string) {
 }
 
 export default async function PageView({ params }: PageProps) {
-  const page = await getPageData(params.slug)
+  const resolvedParams = await params
+  const page = await getPageData(resolvedParams.slug)
 
   if (!page) {
     notFound()
   }
 
   const formatDate = (dateString: string) => {
-    return new Date(dateString).toLocaleDateString(params.locale, {
+    return new Date(dateString).toLocaleDateString(resolvedParams.locale, {
       year: 'numeric',
       month: 'long',
       day: 'numeric'
@@ -207,7 +209,7 @@ export default async function PageView({ params }: PageProps) {
             underline="hover"
             sx={{ display: 'flex', alignItems: 'center' }}
             color="inherit"
-            href={`/${params.locale}`}
+            href={`/${resolvedParams.locale}`}
           >
             <HomeIcon sx={{ mr: 0.5 }} fontSize="inherit" />
             Home