[M4] Migrate User Avatar usages

[mountiny]

Problem

Call sites still pass type={CONST.ICON_TYPE_AVATAR} to the monolithic Avatar, keeping user forking logic in the facade.

Solution

Migrate all user avatar call sites to import and use AvatarUser directly. Remove the user branch, type prop, and AvatarType from the facade once complete. Rename/slim Avatar/index.tsx or remove facade entirely if no call sites remain.

Acceptance criteria

• All ICON_TYPE_AVATAR Avatar usages migrated (~34 call sites)
• AvatarUser exported from @components/Avatar
• type prop removed from public Avatar API
• Unit/UI tests updated

Dependencies

Blocked by: #95597 — [M1] Split Avatar into primitives

Can run in parallel with M3.

Issue Owner

Current Issue Owner: @jmusial