add VAAPI transcoding support via Intel iHD media driver

[jtrotsky]

One of the features of Immich 3.0 is HLS and Real-Time Video transcoding. I wanted to revisit how to get transcoding working on my Intel N150 and was successful but with a bit of a hack to get it working in podman which im not sure is viable:

sh -c 'R=$(podman mount immich_microservices); devfs -m "$R/dev" rule apply path drm unhide; devfs -m "$R/dev" rule apply path "drm/*" unhide mode 0666; devfs -m "$R/dev" rule apply path dri unhide;
devfs -m "$R/dev" rule apply path "dri/*" unhide; podman unmount immich_microservices; podman exec immich_microservices ls /dev/dri/'

feat: add Intel iHD driver for VAAPI hardware transcoding

Add libva-intel-media-driver and libva-utils to the runtime PACKAGES so
Intel iGPUs can hardware-transcode. The image already ships jellyfin-ffmpeg
built with --enable-vaapi and libva, but without iHD_drv_video.so the
driver chain dead-ends.

Verified on an Intel N150 (Twin Lake): 1080p30 H.264 -> HEVC via hevc_vaapi
at ~90 fps (3x realtime), using ~2% of the CPU time of libx265 medium on
the same clip (1.2 s vs 55 s CPU). The same box cannot software-encode
1080p30 HEVC in realtime (0.66x).

Host setup (DRM driver, firmware, /dev/dri passthrough) is documented in
the daemonless.io Immich Hardware Transcoding guide (separate PR).

[ahze]

good catch!! I missed that when porting jellyfin-ffmpeg.