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>

include/cst_parliament_cli.h

@@ -15,6 +15,10 @@ int cst_parliament_cli_login(const char *password, const char *instance_id,
 int cst_parliament_cli_login_and_serve(const char *password,
                                        const char *instance_id,
                                        const char *device_label, int peer_port);
+/* Join as member seat (no chair steal) then start background service. */
+int cst_parliament_cli_join_and_serve(const char *password,
+                                      const char *instance_id,
+                                      const char *device_label, int peer_port);
 int cst_parliament_cli_service(const char *password, const char *instance_id,
                                int peer_port, int foreground);
 int cst_parliament_cli_service_stop(void);

include/cst_version.h

@@ -3,7 +3,7 @@
 
 #define CST_VERSION_MAJOR 0
 #define CST_VERSION_MINOR 9
-#define CST_VERSION_PATCH 22
+#define CST_VERSION_PATCH 23
 
 #define CST_VERSION_STR_(x) #x
 #define CST_VERSION_STR(x) CST_VERSION_STR_(x)