feat!: universal redesign — drop Minecraft stack, single-crate architecture

- remove Java plugins (velocity/paper), dashboard, all MC-specific code
  (handshake, death_code, varint, hostname-HMAC); available in history pre-v0.2
- merge crates/* into one package with src/bin/{rampart,rampart-manager,rampart-cli}
- ProtocolHandler trait + registry (no implementations yet), universal PoW kept
- XDP: universal L3/L4 filter (xdp/core/) + pluggable hook API (xdp/hooks/),
  fix IPv6 saddr bug; clang build verified
- docs: bilingual knowledge base (docs/kb/: attacks x4, defense-levels,
  practice x3), rewrite README/architecture for universal concept
- TODO.md v4.0: <=300-line module limit, competitor benchmark section (ref/)
- deploy/CI/docs cleanup: no MC references, new binary names

cargo build/clippy(-D warnings)/test green (55 tests)

deploy/test/config.test.toml

@@ -3,43 +3,36 @@ address = "0.0.0.0"
 port = 25565
 
 [backend]
-address = "backend"
-port = 25565
+upstreams = ["backend:25566"]
 
-[hmac]
-secret = "test-secret-for-local-dev-only"
-
-[worker]
+[workers]
 count = 4
 
 [limits]
-rate_limit_login_pps = 50
-rate_limit_burst = 100
+handshake_timeout_secs = 5
+max_connections_per_ip = 10
+rate_limit_pps = 50.0
+rate_limit_burst = 100.0
 
 [store]
 redis_url = ""
+blacklist_cache_ttl_secs = 300
 clickhouse_url = "http://clickhouse:8123"
 
 [xdp]
 enabled = false
 interface = "eth0"
 
-[death_code]
-enabled = true
-
-[minecraft]
-ping_timeout_ms = 5000
-handshake_timeout_ms = 10000
-
 [metrics]
 enabled = true
 port = 9090
 
 [logging]
 level = "debug"
+format = "text"
 
 [pow]
-enabled = true
+enabled = false
 difficulty = 4
 
 whitelist = ["127.0.0.1", "::1"]