perf: accept thread + dial backoff; join/peers.json (0.9.23)

Run inbound peer handling on its own thread so outbound dials cannot starve
:9100. Failed peers cool down exponentially. Also land --join (member seat)
and realm/peers.json seed discovery for Tailscale meshes.

Co-authored-by: Cursor <cursoragent@cursor.com>

src/parliament_cli.c

@@ -125,6 +125,40 @@ int cst_parliament_cli_login_and_serve(const char *password,
   return 0;
 }
 
+int cst_parliament_cli_join_and_serve(const char *password,
+                                      const char *instance_id,
+                                      const char *device_label, int peer_port) {
+  char err[256], pwbuf[256];
+  const char *pw = password;
+  if ((!pw || !pw[0]) && resolve_password(pwbuf, sizeof(pwbuf), &pw) != 0)
+    return 1;
+  char *hand =
+      cst_parliament_seat_join(pw, instance_id, device_label, err, sizeof(err));
+  if (!hand) {
+    fprintf(stderr, "%s\n", err[0] ? err : "join failed");
+    if (pw == pwbuf)
+      memset(pwbuf, 0, sizeof(pwbuf));
+    return 1;
+  }
+  fputs(hand, stdout);
+  free(hand);
+  if (cst_parliament_daemon_start(pw, instance_id,
+                                  peer_port > 0 ? peer_port : 9100, err,
+                                  sizeof(err)) != 0) {
+    fprintf(stderr, "warning: service: %s (seat join still valid)\n",
+            err[0] ? err : "start failed");
+    printf("service=failed\n");
+    if (pw == pwbuf)
+      memset(pwbuf, 0, sizeof(pwbuf));
+    return 0;
+  }
+  if (cst_parliament_daemon_running())
+    printf("service=running\n");
+  if (pw == pwbuf)
+    memset(pwbuf, 0, sizeof(pwbuf));
+  return 0;
+}
+
 int cst_parliament_cli_service(const char *password, const char *instance_id,
                                int peer_port, int foreground) {
   char err[256], pwbuf[256];