feat: VDS stress test harness (edge-only) and load-test results

- deploy/test/stress/: multi-IP masked handshake flood (flood.py), legit client
  during attack (legit.py), full orchestration (run-stress.sh), edge Dockerfile
  with socat stub backend and high/defense configs
- docs/research/load-test-report.md: v3 VDS loopback results (2026-08-04)
- README.md: performance table update (4k conn/s raw, 99.6% blocked in defense,
  legit clients RTT 2-6ms during attack)
- docs/testing.md: multi-IP masked stress-test procedure

deploy/test/stress/legit.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python3
+"""Легитимный Minecraft клиент: подключается ВО ВРЕМЯ DDoS и меряет RTT."""
+
+import argparse
+import socket
+import struct
+import time
+
+
+def pack_varint(value):
+    buf = []
+    while True:
+        byte = value & 0x7F
+        value >>= 7
+        if value:
+            byte |= 0x80
+        buf.append(byte)
+        if not value:
+            break
+    return bytes(buf)
+
+
+def make_handshake(host="play.example.com", port=25565, state=2):
+    pkt = bytearray()
+    pkt.extend(pack_varint(0))
+    pkt.extend(pack_varint(767))
+    pkt.extend(pack_varint(len(host)))
+    pkt.extend(host.encode())
+    pkt.extend(struct.pack(">H", port))
+    pkt.extend(pack_varint(state))
+    return pack_varint(len(pkt)) + bytes(pkt)
+
+
+def main():
+    p = argparse.ArgumentParser()
+    p.add_argument("--target", default="127.0.0.1")
+    p.add_argument("--port", type=int, default=25565)
+    p.add_argument("--count", type=int, default=6)
+    p.add_argument("--interval", type=float, default=5.0)
+    p.add_argument("--timeout", type=float, default=10.0)
+    p.add_argument("--name", default="legit")
+    args = p.parse_args()
+
+    for i in range(args.count):
+        t0 = time.time()
+        s = None
+        try:
+            s = socket.create_connection((args.target, args.port), timeout=args.timeout)
+            s.settimeout(args.timeout)
+            s.sendall(make_handshake())
+            resp = s.recv(1)
+            rtt = (time.time() - t0) * 1000
+            ok = len(resp) > 0
+            print(f"[{args.name}#{i}] {'OK' if ok else 'NO_RESP'} rtt={rtt:.1f}ms")
+        except Exception as e:
+            rtt = (time.time() - t0) * 1000
+            print(f"[{args.name}#{i}] FAIL {type(e).__name__}: {e} rtt={rtt:.1f}ms")
+        finally:
+            if s:
+                try:
+                    s.close()
+                except Exception:
+                    pass
+        time.sleep(args.interval)
+
+
+if __name__ == "__main__":
+    main()