feat: add speed-concurrency option to auto pipeline

src/cli.rs

@@ -54,6 +54,10 @@ pub(crate) struct AutoArgs {
     #[arg(long, default_value_t = 10)]
     pub(crate) speed_top: usize,
 
+    /// Stage 3: concurrent downloads during the speed test (1 = most accurate).
+    #[arg(long, default_value_t = 1)]
+    pub(crate) speed_concurrency: usize,
+
     /// Also test IPv6 ranges (off by default).
     #[arg(short = '6', long = "ipv6")]
     pub(crate) ipv6: bool,

src/commands.rs

@@ -25,7 +25,6 @@ const PING_MIN_LATENCY_MS: f64 = 10.0;
 const PING_MAX_LATENCY_MS: f64 = 300.0;
 const LAT_CONCURRENCY: usize = 50;
 const LAT_TIMEOUT: f64 = 5.0;
-const SPEED_CONCURRENCY: usize = 1;
 const SPEED_TIMEOUT: f64 = 10.0;
 const SPEED_BYTES: u64 = 10_000_000;
 
@@ -197,7 +196,7 @@ pub(crate) async fn run_auto(args: AutoArgs) -> Result<()> {
     let speed_results = stage_speed(
         &node,
         &inputs,
-        SPEED_CONCURRENCY,
+        args.speed_concurrency.max(1),
         Duration::from_secs_f64(SPEED_TIMEOUT),
         SPEED_BYTES,
         args.min_speed,