TypeScript check and typing corrections.

frontend/src/utils/docsort.ts

@@ -41,7 +41,7 @@ export const sortedGrouped = (documents: Doc[], order: SortOrder) => {
   // Find the "best" item in each folder (first after sorting = best according to criteria)
   const folderBest = new Map<string, Doc>()
   for (const [folder, docs] of byFolder) {
-    folderBest.set(folder, docs[0])
+    folderBest.set(folder, docs[0]!)
   }
 
   // Sort folders: by path for name sort, by best item for modified/size

frontend/src/utils/index.ts

@@ -70,7 +70,7 @@ export function getFileType(name: string): string {
   const dotIndex = name.lastIndexOf('.')
   if (dotIndex === -1 || dotIndex === name.length - 1) return 'unknown'
   const ext = name.slice(dotIndex + 1).toLowerCase()
-  return Object.keys(filetypes).find(type => filetypes[type].includes(ext)) || 'unknown'
+  return Object.keys(filetypes).find(type => filetypes[type]!.includes(ext)) || 'unknown'
 }
 
 // Prebuilt for fast & consistent sorting