fresnel-fourier iter4 Phase 6 commit C: picture.c VP9 dispatch + 2 buffer-type cases

5 sites:
1. include block: add #include "vp9.h".
2. codec_set_controls: add VP9 case calling vp9_set_controls().
3. codec_store_buffer VAPictureParameterBufferType: VP9 inner case
   memcpy'ing into surface_object->params.vp9.picture.
4. codec_store_buffer VASliceParameterBufferType: VP9 inner case
   memcpy'ing into surface_object->params.vp9.slice.
5. (No reset in RequestBeginPicture — VP9 has no iqmatrix_set/
   probability_set-style flag, Picture/Slice are unconditionally
   populated by VAAPI consumer per frame.)

Per Phase 2 B12: NO buffer.c changes — VP9 uses Picture+Slice+Data
which are already in the iter3 allow-list. Per memory
feedback_runtime_enumerates_allowlists.md plan for Commit D
fix-forward if a runtime miss surfaces; predicted clean.

Verified end-to-end on fresnel:
- vainfo enumerates VAProfileVP9Profile0 alongside H.264 + HEVC.
- LIBVA_DRIVER_NAME=v4l2_request ffmpeg -hwaccel vaapi VP9 decode
  exits 0 (criterion 3 PASS): 5 frames decoded at 0.307x speed,
  cap_pool_init OK, no kernel ioctl errors.
- mpv vp9-vaapi engagement still SW-fallback (iter4-B2 backlog —
  mpv-DRM device-create path doesn't honor LIBVA_DRIVER_NAME the
  way ffmpeg-vaapi does; investigation deferred).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

src/picture.c

@@ -35,6 +35,7 @@
 #include "h265.h"
 #include "mpeg2.h"
 #include "vp8.h"
+#include "vp9.h"
 
 #include <assert.h>
 #include <stdio.h>
@@ -114,6 +115,12 @@ static VAStatus codec_store_buffer(struct request_data *driver_data,
 			       sizeof(surface_object->params.vp8.picture));
 			break;
 
+		case VAProfileVP9Profile0:
+			memcpy(&surface_object->params.vp9.picture,
+			       buffer_object->data,
+			       sizeof(surface_object->params.vp9.picture));
+			break;
+
 		default:
 			break;
 		}
@@ -153,6 +160,12 @@ static VAStatus codec_store_buffer(struct request_data *driver_data,
 			       sizeof(surface_object->params.vp8.slice));
 			break;
 
+		case VAProfileVP9Profile0:
+			memcpy(&surface_object->params.vp9.slice,
+			       buffer_object->data,
+			       sizeof(surface_object->params.vp9.slice));
+			break;
+
 		default:
 			break;
 		}
@@ -257,6 +270,12 @@ static VAStatus codec_set_controls(struct request_data *driver_data,
 			return VA_STATUS_ERROR_OPERATION_FAILED;
 		break;
 
+	case VAProfileVP9Profile0:
+		rc = vp9_set_controls(driver_data, context, surface_object);
+		if (rc < 0)
+			return VA_STATUS_ERROR_OPERATION_FAILED;
+		break;
+
 	default:
 		return VA_STATUS_ERROR_UNSUPPORTED_PROFILE;
 	}