feat(tui): add agent picker and agents list rpc

src/tui/commands.ts

@@ -31,6 +31,8 @@ export function getSlashCommands(): SlashCommand[] {
   return [
     { name: "help", description: "Show slash command help" },
     { name: "status", description: "Show gateway status summary" },
+    { name: "agent", description: "Switch agent (or open picker)" },
+    { name: "agents", description: "Open agent picker" },
     { name: "session", description: "Switch session (or open picker)" },
     { name: "sessions", description: "Open session picker" },
     {
@@ -108,6 +110,7 @@ export function helpText(): string {
     "Slash commands:",
     "/help",
     "/status",
+    "/agent <id> (or /agents)",
     "/session <key> (or /sessions)",
     "/model <provider/model> (or /models)",
     "/think <off|minimal|low|medium|high>",