feat(host): VAAPI codec probe + AMD/Intel packaging + neutral logs (Phase 3)

Polish for AMD/Intel support:
- GameStream serverinfo advertises only codecs the GPU can ACTUALLY encode on
  the VAAPI backend (probed once by opening a tiny encoder per codec). AV1
  encode is narrow (Intel Arc/Xe2+, AMD RDNA3+/RDNA4) and an old iGPU may lack
  HEVC, so a Moonlight client never negotiates a codec the encoder can't open.
  NVENC/Windows keep the Moonlight-validated static mask. Validated on a Radeon
  780M: h264/h265/av1 all probe true -> mask unchanged (65793).
- Packaging: Recommends mesa-va-drivers + intel-media-va-driver (deb) /
  mesa-va-drivers + intel-media-driver (rpm) so the auto-selected VAAPI backend
  works out of the box on AMD/Intel; NVIDIA boxes can --no-install-recommends.
  (Fedora note: stock mesa-va-drivers disables HEVC/AV1 -- needs the freeworld
  variant from RPM Fusion.)
- De-NVIDIA-fy the user-facing encoder log/context strings ("open NVENC" ->
  "open video encoder") now that VAAPI is a first-class backend.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

packaging/debian/build-deb.sh

@@ -109,10 +109,13 @@ DEPENDS="$SHDEPS, libei1, pipewire, wireplumber"
 # ffmpeg: Ubuntu's ffmpeg ships the NVENC-enabled libav* the binary links AND is the encoder
 # runtime; the libav* sonames are already hard Depends via shlibdeps, so the ffmpeg metapackage
 # is a Recommends. gamescope = a ready compositor backend; pipewire-pulse = desktop audio.
+# mesa-va-drivers / intel-media-va-driver = the VAAPI encode drivers for AMD (radeonsi) and Intel
+# (iHD) — pulled by default so the auto-selected VAAPI backend works out of the box; NVIDIA boxes
+# don't need them (NVENC comes from the driver) and can --no-install-recommends.
 # punktfunk-web = the management web console (pairing + status) every user needs — a separate
 # Architecture:all .deb; Recommends so `apt install punktfunk-host` pulls it by default, while a
 # headless/encoding-only box can opt out with --no-install-recommends.
-RECOMMENDS="ffmpeg, gamescope, pipewire-pulse, punktfunk-web"
+RECOMMENDS="ffmpeg, gamescope, pipewire-pulse, mesa-va-drivers, intel-media-va-driver, punktfunk-web"
 SUGGESTS="kwin-wayland, mutter"
 
 INSTALLED_KB="$(du -k -s "$STAGE" | cut -f1)"