color: input colorspace auto-detection, HDR export tags, LGG/white balance nodes, more LUT formats, waveform parade

- media color primaries/transfer tags now flow from the FFmpeg probe
  through VideoParams into Footage::get_colorspace_to_use(); precedence
  is user override > media tags > project default
- export nclc tags derive from the output colorspace (PQ/HLG/BT.2020,
  P3, sRGB, Rec.601, Rec.709) instead of hardcoded BT.709
- new OCIO Color Grading (Log) node (lift/gamma/gain) and White Balance
  node (kelvin temperature + tint, HDR-safe)
- LUT whitelist extended to 9 OCIO-supported formats
- waveform scope gains an RGB parade mode (GPU and software paths)
- tests updated for the new colorspace precedence

app/node/project/footage/footage.cpp

@@ -126,11 +126,20 @@ Rational Footage::verify_length_internal(Track::Type type) const
 
 QString Footage::get_colorspace_to_use(const VideoParams &params) const
 {
-	if (params.colorspace().isEmpty()) {
-		return project()->color_manager()->get_default_input_color_space();
-	} else {
+	if (!params.colorspace().isEmpty()) {
+		// The user explicitly set this stream's colorspace
 		return params.colorspace();
 	}
+
+	// No override: try auto-detecting from the media's color tags
+	const QString detected =
+		project()->color_manager()->get_colorspace_for_ffmpeg_tags(
+			params.color_primaries(), params.color_transfer());
+	if (!detected.isEmpty()) {
+		return detected;
+	}
+
+	return project()->color_manager()->get_default_input_color_space();
 }
 
 void Footage::clear()