v0.5.0: Add syslog support, fix TCP send/both, EC-SRP5 server auth

New features:
- --syslog <address:port> sends structured events to remote syslog (RFC 5424 UDP)
  Events: AUTH_SUCCESS, AUTH_FAILURE, TEST_START, TEST_END, TEST_RESULT
- EC-SRP5 authentication for both client and server modes
- TCP multi-connection support (session tokens, all 3 directions)

Bug fixes since v0.2.0:
- EC-SRP5 server: fixed gamma parity (was 50% auth failure rate)
- EC-SRP5 server: use lift_x not redp1 for verification
- TCP send direction: server sends 12-byte status messages to client
- TCP both direction: TX loop injects status between data packets
- TCP data: send all zeros (no 0x07 header that MikroTik rejected)
- TCP disconnect detection: running flag set on EOF
- UDP multi-connection: unconnected socket accepts all source ports

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/main.rs

@@ -4,6 +4,7 @@ mod client;
 mod ecsrp5;
 mod protocol;
 mod server;
+pub mod syslog_logger;
 
 use clap::Parser;
 use tracing_subscriber::EnvFilter;
@@ -65,6 +66,10 @@ struct Cli {
     #[arg(short = 'n', long = "nat")]
     nat: bool,
 
+    /// Send logs to remote syslog server (e.g., 192.168.1.1:514)
+    #[arg(long = "syslog")]
+    syslog: Option<String>,
+
     /// Verbose logging (repeat for more: -v, -vv, -vvv)
     #[arg(short = 'v', long = "verbose", action = clap::ArgAction::Count)]
     verbose: u8,
@@ -87,6 +92,13 @@ async fn main() -> anyhow::Result<()> {
         .with_target(false)
         .init();
 
+    // Initialize syslog if requested
+    if let Some(ref syslog_addr) = cli.syslog {
+        if let Err(e) = syslog_logger::init(syslog_addr) {
+            eprintln!("Warning: failed to initialize syslog to {}: {}", syslog_addr, e);
+        }
+    }
+
     if cli.server {
         // Server mode
         tracing::info!("Starting btest server on port {}", cli.port);