feat: initial SOCKS5 proxy with chain support

Asyncio-based SOCKS5 server that tunnels connections through
configurable chains of SOCKS5, SOCKS4/4a, and HTTP CONNECT proxies.
Tor integration via standard SOCKS5 hop.

ROADMAP.md

@@ -0,0 +1,30 @@
+# s5p -- Roadmap
+
+## v0.1.0 (current)
+
+- [x] SOCKS5 server (CONNECT command)
+- [x] Proxy chaining (SOCKS5, SOCKS4/4a, HTTP CONNECT)
+- [x] Per-hop authentication
+- [x] YAML config + CLI flags
+- [x] DNS leak prevention
+
+## v0.2.0
+
+- [ ] SOCKS5 server authentication (username/password)
+- [ ] Tor control port integration (circuit renewal via NEWNYM)
+- [ ] Connection retry with configurable backoff
+- [ ] Metrics (connections/sec, bytes relayed, hop latency)
+
+## v0.3.0
+
+- [ ] UDP ASSOCIATE support (SOCKS5 UDP relay)
+- [ ] BIND support
+- [ ] Chain randomization (random order, random subset)
+- [ ] Hot-reload config on SIGHUP
+
+## v1.0.0
+
+- [ ] Stable API and config format
+- [ ] Comprehensive test suite with mock proxies
+- [ ] Systemd service unit
+- [ ] Performance benchmarks