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

ffmpeg_bridge/src/decoder.cpp

@@ -435,6 +435,8 @@ int fb_decoder_get_stream_info(const FBDecoder *decoder, FBStreamInfo *out)
 	out->field_order = decoder->codec_ctx ? decoder->codec_ctx->field_order :
 											AV_FIELD_UNKNOWN;
 	out->color_range = par->color_range;
+	out->color_primaries = par->color_primaries;
+	out->color_trc = par->color_trc;
 	out->sample_rate = par->sample_rate;
 	out->sample_format = par->format;
 	out->channel_layout_mask = fb::validate_stream_channel_layout_mask(s);