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/portal/portal-nav.tsx

@@ -25,7 +25,7 @@ export function PortalNav() {
             return (
               <Link
                 key={item.href}
-                href={item.href as any}
+                href={item.href}
                 className={cn(
                   'flex items-center gap-2 px-4 py-3 text-sm font-medium border-b-2 transition-colors whitespace-nowrap',
                   isActive