fix(client,protocol): EINTR-safe sends, armed abort, keepalive drain grace, TLS WANT_WRITE

src/client/client_send.h

@@ -13,6 +13,10 @@
  * receiver can clean up before the client exits. */
 extern volatile sig_atomic_t client_abort_requested;
 bool client_abort_pending(void);
+/* Arm/disarm abort handling around the network phase.  While disarmed, a
+ * SIGINT/SIGTERM takes the default action (immediate termination) so local-only
+ * modes are not left unresponsive.  Defined in client_cli.c. */
+void client_set_abort_armed(bool armed);
 
 /* Both sender entry points BORROW `config` for the duration of the call; they
  * never free it, and the caller retains ownership (freeing it with