### Problem
`TabButton` and `AvatarOrIcon` stories (in both `twenty-ui` and
`twenty-ui-deprecated`) used random remote image URLs —
`picsum.photos/192/192` and `i.pravatar.cc/300`. Each Argos run fetched
a different image, producing false-positive pixel diffs.
This is the image counterpart to #21412, which froze framer-motion
animations for the same reason.
### Fix
Replace all 6 random URLs with `AVATAR_URL_MOCK` — a fixed base64 data
URI already used across avatar stories. It's deterministic and
network-free, so screenshots are now stable across runs.
- `twenty-ui` / `twenty-ui-deprecated` → `TabButton.stories.tsx` (×2
each)
- `twenty-ui` / `twenty-ui-deprecated` → `AvatarOrIcon.stories.tsx` (×1
each)
Note: this changes the rendered image content, so it adds new baselines
(one-time Argos approval, not flakiness).
Raphaël Bosi
7da6f25aaf