Investigate Pinet skin emoji drift after resuming a follower session

[gugu91]

Maintainer-requested follow-up from Slack thread 1777815587.943179.

Context

Drehy Wave was resurrected by resuming the original Pi session/stable id. The agent id and session context came back correctly, but the display emoji changed from the prior skin-assigned 🐦 to 🫎. The maintainer expected the skin emojis/character assignment to be hardcoded/stable for the skin.

Observed during recovery:

• Original agent: Drehy Wave / 7daefa35-d794-4196-887d-fc0964692389
• Original stored state showed agentEmoji: "🐦" in the session file.
• After resume + /pinet follow, broker roster showed same name/id/stable session but emoji 🫎.
• Skin: cosmere

Ask

Investigate why the Pinet follower resume/follow path can change the emoji for a skin-assigned agent even when the same Pi session/stable id is resumed. Determine whether this is intended, a persistence bug, or a registration/skin assignment bug.

Acceptance criteria

• Explain the root cause.
• If it is a bug, implement a fix preserving skin-assigned identity across resume/reconnect.
• Add/adjust regression coverage for the resume/follow identity path.
• Report whether any existing persisted runtime state needs migration/repair.

No secret values should be logged or exposed.