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/lib/services/storage.ts

@@ -16,7 +16,6 @@ export function sanitizeFilename(name: string): string {
   return name
     .replace(/[/\\:]/g, '')       // strip path chars
     .replace(/\x00/g, '')          // strip null bytes
-    // eslint-disable-next-line no-control-regex
     .replace(/[\x01-\x1f\x7f]/g, '') // strip control chars
     .trim()
     .slice(0, 255);