Fix CPU reporting: MikroTik uses 0x80|pct encoding, add CPU to CSV

- MikroTik encodes CPU as 0x80 | percentage (high bit flag)
- Deserialize: mask with 0x7F and cap at 100
- Serialize: set high bit (0x80 | cpu) to match MikroTik format
- CSV now includes local_cpu_pct and remote_cpu_pct columns
- Both client and server write CPU to CSV

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

src/main.rs

@@ -226,9 +226,11 @@ async fn main() -> anyhow::Result<()> {
         // Write CSV if enabled
         if csv_output::is_enabled() {
             let auth_type = if cli.auth_user.is_some() { "auth" } else { "none" };
+            let local_cpu = cpu::get();
+            let remote_cpu = shared_state.remote_cpu.load(std::sync::atomic::Ordering::Relaxed);
             csv_output::write_result(
                 &host, cli.port, proto_str, dir_str,
-                elapsed, total_tx, total_rx, total_lost, auth_type,
+                elapsed, total_tx, total_rx, total_lost, local_cpu, remote_cpu, auth_type,
             );
         }
     } else {