AvatarImage allows missing alt text

[adliebe]

src/components/ui/avatar.tsx defines AvatarImage as a thin wrapper around <img>, but the wrapper currently does not guarantee an alt attribute.

That leaves multiple existing call sites able to render avatar images without alt text. The current lint output also flags the component with jsx-a11y/alt-text.

Repro on current master:

pnpm install --ignore-scripts --frozen-lockfile
pnpm exec eslint src/components/ui/avatar.tsx src/components/ui/avatar.test.tsx

Current result includes:

src/components/ui/avatar.tsx
  23:3  warning  img elements must have an alt prop, either with meaningful text, or an empty string for decorative images  jsx-a11y/alt-text

Expected: AvatarImage should either preserve a caller-provided alt, or render a safe empty alt by default for decorative avatar images.