Narrow component prop types, remove unused props and dead code (#2838)

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>

shared/ui/AvatarUpload.astro

@@ -1,9 +1,10 @@
 ---
 import Icon from './Icon.astro'
+import type { AvatarSize } from './Avatar.astro'
 
 interface Props {
   class?: string
-  size?: string
+  size?: AvatarSize | undefined
 }
 
 const { class: className, size } = Astro.props