feat(agents): let an agent choose who may mention-wake it (respond-to anyone/allowlist in the agent editor) #3369

What

In Buzz 1.0 the agent editor exposes only Harness / Model / Thinking. The kind-30177 record has a respond_to field (default owner-only), but shareable() drops it and no UI edits it, so an app-created agent can only ever be woken by its owner or an NIP-OA-attested sibling (fromOwner(), src/features/agents/owner-attestation.ts).

Result: two people on different accounts cannot @-mention each other's agents in a shared channel; the p tag is delivered but the wake gate drops it.

Request

Bring back the respond-to setting (Only me / Anyone / allowlist) in the agent editor (it existed in 0.X desktop as RespondToField), and carry it in share cards, so anyone/allowlist agents can be woken by other accounts' mentions in channels.

Evidence

• src/features/agents/relay-removal.ts:92 publishes respond_to: "owner-only" as default; docs/relay-queries.md:104-127 requires the field.
• src/features/agents/agent-share.ts shareable() omits respond_to; docs/agents.md:1613 says import drops it.
• Gate: fromOwner() in src/features/agents/owner-attestation.ts:142-151, called from src/bundled/goose/runtime.ts:402-407.
• Related open PR: feat(agents): remove workflow restriction flag, explain ignored mentions, warn on owner-only agent mentions #3141 (explains ignored mentions, warns on owner-only).