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>

components/admin/pages/image-upload.tsx

@@ -231,16 +231,16 @@ export function ImageUpload({ open, onClose, onImageSelect }: ImageUploadProps)
             {loadingMedia ? (
               <Typography>Loading media files...</Typography>
             ) : (
-              <Grid container spacing={2}>
+              <Box sx={{ display: 'flex', flexWrap: 'wrap', gap: 2 }}>
                 {mediaFiles.length === 0 ? (
-                  <Grid item xs={12}>
-                    <Typography color="text.secondary" textAlign="center">
+                  <Box sx={{ width: '100%', textAlign: 'center' }}>
+                    <Typography color="text.secondary">
                       No images found. Upload some images first.
                     </Typography>
-                  </Grid>
+                  </Box>
                 ) : (
                   mediaFiles.map((file) => (
-                    <Grid item xs={12} sm={6} md={4} key={file.id}>
+                    <Box key={file.id} sx={{ width: { xs: '100%', sm: '48%', md: '31%' } }}>
                       <Card>
                         <CardMedia
                           component="img"
@@ -267,10 +267,10 @@ export function ImageUpload({ open, onClose, onImageSelect }: ImageUploadProps)
                           </Button>
                         </CardActions>
                       </Card>
-                    </Grid>
+                    </Box>
                   ))
                 )}
-              </Grid>
+              </Box>
             )}
           </Box>
         )}