fix: recover profile and avatar loading

[Just-Insane]

Description

Fixes profile and avatar loading regressions introduced around the MSC4440 bio compatibility work.

This PR addresses two related problems:

• Own profile data could disappear when useUserProfile encountered gay.fomx.biography in an unexpected shape or when the field was missing entirely.
• Avatar components could get stuck in fallback mode after a transient image load failure, causing the account avatar and other avatars to disappear until a full reload.

The fix does three things:

• parses gay.fomx.biography defensively with optional access instead of assuming m.text[0].body always exists
• retries profile fetches when the cache was previously poisoned into an _fetched-only state after normalization failed
• resets avatar error state when the image src changes so transient media/auth failures can recover on later renders

This was verified against the broken Account settings / account switcher behavior where avatar, banner, bio, status, and pronouns could appear missing.

Fixup of #559

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings

AI disclosure:

• Partially AI assisted (GitHub Copilot)

useUserProfile.ts: Hardened MSC4440 bio parsing so missing or malformed gay.fomx.biography data does not throw during normalization, and allowed refetching when the profile cache only contains _fetched: true from a prior failed normalization.

UserAvatar.tsx and RoomAvatar.tsx: Reset local image error state when src changes so a temporary image load failure does not permanently lock the component into fallback rendering.