Add HTTP/HTTPS protocol support for snapshots and streams

Register http, https, httpx handlers with content-type detection:
- image/jpeg: single JPEG snapshots via go2rtc image.Open
- multipart/x-mixed-replace: MJPEG streams via mpjpeg.Open
- application/vnd.apple.mpegurl: HLS via hls.OpenURL
- auto-detect fallback via magic.Open (MPEG-TS, raw MJPEG, etc.)

Uses go2rtc tcp.Do for Basic + Digest auth and TLS handling.

pkg/tester/source_http.go

@@ -0,0 +1,66 @@
+package tester
+
+import (
+	"errors"
+	"fmt"
+	"net/http"
+	"strings"
+
+	"github.com/AlexxIT/go2rtc/pkg/core"
+	"github.com/AlexxIT/go2rtc/pkg/hls"
+	"github.com/AlexxIT/go2rtc/pkg/image"
+	"github.com/AlexxIT/go2rtc/pkg/magic"
+	"github.com/AlexxIT/go2rtc/pkg/mpjpeg"
+	"github.com/AlexxIT/go2rtc/pkg/tcp"
+)
+
+func init() {
+	RegisterSource("http", httpHandler)
+	RegisterSource("https", httpHandler)
+	RegisterSource("httpx", httpHandler)
+}
+
+// httpHandler -- HTTP GET with content-type detection.
+// Supports JPEG snapshots, MJPEG streams, HLS, MPEG-TS, and auto-detect via magic.Open.
+// Uses go2rtc tcp.Do for Basic + Digest auth and TLS handling.
+// ex. "http://admin:pass@192.168.1.100/cgi-bin/snapshot.cgi"
+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)
+	if err != nil {
+		return nil, fmt.Errorf("http: request: %w", err)
+	}
+
+	res, err := tcp.Do(req)
+	if err != nil {
+		return nil, fmt.Errorf("http: dial: %w", err)
+	}
+
+	if res.StatusCode != http.StatusOK {
+		tcp.Close(res)
+		return nil, errors.New("http: " + res.Status)
+	}
+
+	ct := res.Header.Get("Content-Type")
+	if i := strings.IndexByte(ct, ';'); i > 0 {
+		ct = ct[:i]
+	}
+
+	var ext string
+	if i := strings.LastIndexByte(req.URL.Path, '.'); i > 0 {
+		ext = req.URL.Path[i+1:]
+	}
+
+	switch {
+	case ct == "application/vnd.apple.mpegurl" || ext == "m3u8":
+		return hls.OpenURL(req.URL, res.Body)
+	case ct == "image/jpeg":
+		return image.Open(res)
+	case ct == "multipart/x-mixed-replace":
+		return mpjpeg.Open(res.Body)
+	}
+
+	return magic.Open(res.Body)
+}