feat: add peer metadata (peerType, channel, model) and cwd to peer list

Extend the WS hello handshake with optional peerType, channel, and model
fields so peers can advertise what kind of client they are. The broker
stores these in-memory on PeerConn and returns them (along with cwd) in
the peers_list response. CLI peers command and MCP list_peers tool now
display the new metadata.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/cli/src/mcp/server.ts

@@ -322,7 +322,13 @@ Your message mode is "${messageMode}".
             const peerLines = peers.map((p) => {
               const summary = p.summary ? ` — "${p.summary}"` : "";
               const groupsStr = p.groups?.length ? ` [${p.groups.map(g => `@${g.name}${g.role ? ':' + g.role : ''}`).join(', ')}]` : "";
-              return `- **${p.displayName}** [${p.status}]${groupsStr} (${p.pubkey.slice(0, 12)}…)${summary}`;
+              const meta: string[] = [];
+              if (p.peerType) meta.push(`type:${p.peerType}`);
+              if (p.channel) meta.push(`channel:${p.channel}`);
+              if (p.model) meta.push(`model:${p.model}`);
+              const metaStr = meta.length ? ` {${meta.join(", ")}}` : "";
+              const cwdStr = p.cwd ? ` cwd:${p.cwd}` : "";
+              return `- **${p.displayName}** [${p.status}]${groupsStr}${metaStr} (${p.pubkey.slice(0, 12)}…)${cwdStr}${summary}`;
             });
             sections.push(`${header}\n${peerLines.join("\n")}`);
           }