Video offload: Mesa etnaviv in the image, forgectrl pinned, the H.264 stream in the catalog

The stream conversion now runs on the GC880 when the image carries the
GL stack, and /cam/h264 serves the same picture as fragmented MP4 in a
fraction of MJPEG's bytes (forgectrl 6573abd). This side supplies what
that needs and holds it to account:

- Distro: opengl stays a feature, with mesa trimmed to exactly the
  path used (gallium etnaviv, GLES/EGL/GBM, no GLX, no display
  platforms). Image: libegl-mesa, libgles2-mesa, libgbm,
  mesa-megadriver. forgectrl dlopens them, so an image without them
  still streams on NEON. Platform change: the next campaign is full.
- forgetest: camera.h264-stream exercises the endpoint end to end
  (codec header, init segment, media fragments, /cam/status encoder
  state) and accepts a clean 503 on a machine without the stack;
  the camera covers name the new forgectrl files.
- VIDEO.md 5.6 now describes both streams and why H.264 earns its
  place (the WiFi transmit path measures about 7 percent of the core
  per MB/s sent); BRINGUP records the bench-validation checklist as
  Next work item 20, including the release-size watch: mesa must fit
  the 200 MiB slot gate.

meta-forgefirm/recipes-forgefirm/forgectrl/forgectrl-pin.inc

@@ -2,5 +2,5 @@
 # only SRCREV and PV here - the image manifest leaves *-pin.inc out of the
 # layer content hash because the component entry already identifies the
 # pinned source (forgefirm-image-manifest.bbclass).
-SRCREV = "3acd66425dd53b3a8b16ae175ec442a4d057b9ac"
+SRCREV = "6573abd725e885f0a56463cc83bcb1863525ff77"
 PV = "0.1.0"

meta-forgefirm/recipes-forgefirm/images/forgefirm-image.bb

@@ -35,6 +35,11 @@ IMAGE_INSTALL:remove = "gfui-client"
 # VIRTUAL-RUNTIME_base-utils-syslog (conf/distro/forgefirm.conf).
 IMAGE_INSTALL:append = " grblhal-glowforge forgectrl gfhome gfcloud v4l-utils fwup ffboot slotmigrate forgefirm-logging"
 
+# Mesa GLES2/EGL on etnaviv for forgectrl's GPU demosaic (loaded with
+# dlopen at runtime; forgectrl itself has no build-time GL dependency,
+# and without these packages it falls back to the NEON path).
+IMAGE_INSTALL:append = " libegl-mesa libgles2-mesa libgbm mesa-megadriver"
+
 # NXP's firmware EULA covers the i.MX VPU/EPDC blobs the BSP installs, so the
 # image ships the license text with them (/usr/share/licenses/firmware-imx).
 # The SDMA firmware brings its own -license package through linux-firmware.