Hotfix: stream avatar readiness and visual correctness

[rndrntwrk]

Summary

The stream client can report healthy before the followed duel avatars are actually resolved, and personal staging also showed an asset/CSP path that allowed fallback capsules instead of loaded characters.

Scope

• gate stream health/readiness on followed-avatar readiness during active duel phases
• surface avatar_not_ready as a degraded renderer-health reason until the followed avatar resolves
• keep the local-only Pages asset/CSP normalization out of the upstream PR scope

Why This Is Hotfix Scope

This is a direct viewer-facing regression on staging derived from main. The stream can look healthy while the rendered duel is visually wrong.

Acceptance

• active duel characters render as actual avatars, not fallback capsules
• stream health does not go green before avatar readiness
• browser/soak probes can distinguish healthy from visually degraded