Desktop: Selected people chips show truncated pubkeys instead of display names

## Summary

In **Edit agent → Who can send instructions → Selected people**, the selected-user chips render truncated hex pubkeys (e.g. `3fa38fb8…a2ef`) instead of display names / NIP-05 handles. Search results already show names, but chips discard that metadata after add.

This makes it hard to tell who was granted agent access (computer/files/tools) when revisiting the allowlist.

## Repro

1. Open Edit agent on a managed agent.
2. Set **Who can send instructions** to **Selected people**.
3. Search for a community member by name and Add them.
4. Observe the chip shows truncated pubkey, not the name from search.
5. Close and reopen Edit agent — same truncated pubkey chips (no profile re-lookup).

## Expected

Chips show `displayName` → `nip05Handle` → truncated pubkey fallback, with avatar when available — same pattern as `PersonaShareRecipients` / `SelectedRecipientChip`.

## Actual

Chips always use `truncatePubkey` + `` with `avatarUrl={null}` in `AllowlistPicker` (`desktop/src/features/agents/ui/RespondToField.tsx`). Allowlist state is correctly persisted as hex pubkey strings; only the chip label needs profile resolution (e.g. `useUsersBatchQuery`).

## Notes

- Persistence should remain hex pubkeys (`respond_to_allowlist`).
- Related but distinct from allowlist persistence bugs (#2501, #3030, #4487) and people-search matching (#3353).