Add 15s timeout for HTTP handler requests

Cameras under load may accept TCP connection but never respond,
hanging tester workers indefinitely. Context timeout on the HTTP
request ensures workers are released.

pkg/tester/source_http.go

@@ -1,10 +1,12 @@
 package tester
 
 import (
+	"context"
 	"errors"
 	"fmt"
 	"net/http"
 	"strings"
+	"time"
 
 	"github.com/AlexxIT/go2rtc/pkg/core"
 	"github.com/AlexxIT/go2rtc/pkg/hls"
@@ -27,22 +29,29 @@ func init() {
 func httpHandler(rawURL string) (core.Producer, error) {
 	rawURL, _, _ = strings.Cut(rawURL, "#")
 
-	// httpx -> https with insecure TLS (handled inside tcp.Do)
-	req, err := http.NewRequest("GET", rawURL, nil)
+	ctx, cancel := context.WithTimeout(context.Background(), 15*time.Second)
+
+	req, err := http.NewRequestWithContext(ctx, "GET", rawURL, nil)
 	if err != nil {
+		cancel()
 		return nil, fmt.Errorf("http: request: %w", err)
 	}
 
 	res, err := tcp.Do(req)
 	if err != nil {
+		cancel()
 		return nil, fmt.Errorf("http: dial: %w", err)
 	}
 
 	if res.StatusCode != http.StatusOK {
+		cancel()
 		tcp.Close(res)
 		return nil, errors.New("http: " + res.Status)
 	}
 
+	// cancel on success is not called -- context expires naturally,
+	// connection lifetime is managed by prod.Stop()
+
 	ct := res.Header.Get("Content-Type")
 	if i := strings.IndexByte(ct, ';'); i > 0 {
 		ct = ct[:i]