feat(cli): peer list self-marking + send self-DM guard

closes the "DM looped back to my own inbox" footgun.

what was happening: peer list returns one row per presence,
including the caller's own session AND its sibling sessions.
the cli filtered out the exact-session row but left siblings
unlabeled — copying their pubkey from peer list silently
targeted your own sibling, and the message arrived in "your
own inbox" because the sender was you.

fix is two-part.

(1) peer list — tag rows whose memberPubkey matches the
caller's stable JoinedMesh.pubkey:
  ● displayName (this session) — the exact session running
                                 the cli call
  ● displayName (your other session) — sibling session of
                                       your own member
visually identical otherwise; just the marker.

(2) claudemesh send — refuse a target that exactly matches the
caller's own member pubkey on the mesh, with a hint pointing
at --self for the rare intentional sibling-DM case.

both changes additive — existing scripts that pass display
names or other peers' pubkeys behave identically.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

apps/cli/src/entrypoints/cli.ts

@@ -318,7 +318,7 @@ async function main(): Promise<void> {
 
     // Messaging
     case "peers": { const { runPeers } = await import("~/commands/peers.js"); await runPeers({ mesh: flags.mesh as string, json: flags.json as boolean | string | undefined }); break; }
-    case "send": { const { runSend } = await import("~/commands/send.js"); await runSend({ mesh: flags.mesh as string, priority: flags.priority as string, json: !!flags.json }, positionals[0] ?? "", positionals.slice(1).join(" ")); break; }
+    case "send": { const { runSend } = await import("~/commands/send.js"); await runSend({ mesh: flags.mesh as string, priority: flags.priority as string, json: !!flags.json, self: !!flags.self }, positionals[0] ?? "", positionals.slice(1).join(" ")); break; }
     case "inbox": { const { runInbox } = await import("~/commands/inbox.js"); await runInbox({ json: !!flags.json }); break; }
     case "state": {
       const sub = positionals[0];