Fix all ESLint errors: remove unused imports, replace any types

- Remove ~60 unused imports and variables across 88 files
- Replace ~80 `any` type annotations with proper types (unknown,
  Record<string, unknown>, or specific types)
- Prefix unused callback args with underscore
- Fix unescaped JSX entities
- Lint now passes cleanly (0 errors, 2 intentional img warnings)

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/components/files/file-grid.tsx

@@ -45,7 +45,7 @@ function formatBytes(bytes: string | null): string {
 
 function FileIcon({ mimeType }: { mimeType: string | null }) {
   if (!mimeType) return <FileText className="h-8 w-8 text-muted-foreground" />;
-  if (mimeType.startsWith('image/')) return <Image className="h-8 w-8 text-blue-500" />;
+  if (mimeType.startsWith('image/')) return <Image className="h-8 w-8 text-blue-500" alt="" />;
   if (mimeType === 'application/pdf') return <FileText className="h-8 w-8 text-red-500" />;
   if (
     mimeType === 'application/vnd.ms-excel' ||