fix: proxy ERROR loop, BBR test backpressure, O(1) u_free, test ordering

- tcp_proxy: ERROR silently dropped (no ERROR->ERROR loop), Russian removed from logs
- etcp_bbr: swap min(lo) and max(4*mss) in bbr_bound_cwnd_for_inflight_model
- test_etcp_bbr: fix cwnd comparison (packets vs bytes)
- ll_queue: double-put detection (abort), Floyd cycle detection in consistency check
- ll_queue: QUEUE_DEBUG commented out (was always-on, O(N) per put)
- mem: u_free_impl now O(1) via doubly-linked list, double-free detection
- bbr_integration: queue_waiter_wait + call_soon backpressure (threshold=1)
- tests/Makefile.am: fast tests first, *.log cleanup before run

lib/ll_queue.h

@@ -12,7 +12,7 @@
     #include <pthread.h>
 #endif
 
-#define QUEUE_DEBUG 1
+//#define QUEUE_DEBUG 1       // раскомментировать для отладки очереди
 //#define QUEUE_THREAD_CHECK 1  // 0 to disable
 
 /**