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/configs/edge-defense.toml

@@ -0,0 +1,46 @@
+[bind]
+address = "0.0.0.0"
+port = 25565
+
+[backend]
+address = "127.0.0.1"
+port = 25566
+
+[hmac]
+secret = "test_secret_32_bytes_long_for_integration_test"
+
+[workers]
+count = 2
+
+[limits]
+handshake_timeout_secs = 5
+max_connections_per_ip = 10
+rate_limit_status_pps = 2
+rate_limit_login_pps = 5
+rate_limit_burst = 10
+
+[store]
+redis_url = ""
+blacklist_cache_ttl_secs = 300
+
+[xdp]
+enabled = false
+interface = "eth0"
+
+[death_code]
+enabled = true
+ban_duration_secs = 3600
+
+[metrics]
+enabled = true
+port = 9090
+
+[logging]
+level = "debug"
+format = "text"
+
+[pow]
+enabled = false
+difficulty = 4
+
+whitelist = ["127.0.0.1", "::1"]

deploy/test/stress/configs/edge-high.toml

@@ -0,0 +1,46 @@
+[bind]
+address = "0.0.0.0"
+port = 25565
+
+[backend]
+address = "127.0.0.1"
+port = 25566
+
+[hmac]
+secret = "test_secret_32_bytes_long_for_integration_test"
+
+[workers]
+count = 2
+
+[limits]
+handshake_timeout_secs = 5
+max_connections_per_ip = 100000
+rate_limit_status_pps = 100000
+rate_limit_login_pps = 100000
+rate_limit_burst = 100000
+
+[store]
+redis_url = ""
+blacklist_cache_ttl_secs = 300
+
+[xdp]
+enabled = false
+interface = "eth0"
+
+[death_code]
+enabled = true
+ban_duration_secs = 3600
+
+[metrics]
+enabled = true
+port = 9090
+
+[logging]
+level = "debug"
+format = "text"
+
+[pow]
+enabled = false
+difficulty = 4
+
+whitelist = ["127.0.0.1", "::1"]