BREAKING: Native p2ns.core RPC — invite.deliver, remove legacy invite channel

Replace RPC-to-string adapters and processCoreRequestMessage (~470 lines) with
typed handlers in core-swarm-handlers.js. Autopass invite wire now uses
invite.deliver RPC only; p2ns.core-invite protomux channel is removed.

- Add core-rpc-contract.js (METHODS, INVITE_STATUS) and core-swarm-handlers.js
  with shared processInviteWire for deliver, relay, and pairing
- core-rpc.js: deliverInviteWire via invite.deliver; invite.request returns
  { status, reason, inviteId }; invite.ack carries optional inviteId
- p2ns.js: register native handlers; slim p2ns.core-request (lifecycle only);
  proactive invite ack tracks inviteId; fix missing invite.queued handler
- proxy-server: channel-manager + shared handlers (no p2ns.core-invite strings)
- Tests: core-swarm-handlers.test.js, core-invite-rpc-integration.js; extend test:core-rpc
- Docs: PLUGIN_SDK RPC table; consensus.removeDomain in longform/RESTAPI/glossary

docs/RESTAPI.md

@@ -393,7 +393,7 @@ The P2NS (Peer-to-Peer Name System) admin backend API, hosted at `https://p2ns.a
 
 ### 17. POST /api/remove-domain
 - **Description**: Removes a domain. Behavior depends on consensus status:
-  - **Resolved Claimant**: Performs full cleanup removing all claims and votes for the domain, broadcasts `remove_domain:` to trigger other peers to clean up
+  - **Resolved Claimant**: Performs full cleanup removing all claims and votes for the domain, broadcasts `consensus.removeDomain` RPC to trigger other peers to clean up
   - **Conflict Claim**: Removes only your own claim and votes, broadcasts `removeConflictDomainClaim:` notification (other peers preserve their claims)
 - **Request Body**: JSON with `domain` (string).
 - **Response**: Plain text `OK` on success, error message on failure.