Add NVENC (h264_nvenc, hevc_nvenc) encoder support for Linux builds

[JonnyBurger]

This PR copies the changes from #16 so CircleCI runs on a branch owned by a maintainer account.\n\nOriginal PR: #16

[willy-scr]

Hi @JonnyBurger, I noticed the CircleCI Linux builds failed on this PR (build-linux-x64-gnu, build-linux-x64-musl, build-linux-arm-gnu, build-linux-arm-musl all failed).

I can't access the CircleCI logs directly — could you share what the error was?

My best guess is either:

1. nv-codec-headers git clone failed in the Docker container
2. make install PREFIX=remotion failed (maybe needs SUDO or different make flags)
3. FFmpeg configure couldn't find the ffnvcodec pkg-config file

Happy to fix once I know the error!

[willy-scr]

The CI build fails because compile-nvenc.mjs references a non-existent tag:

const NV_CODEC_HEADERS_TAG = "n12.2.16.0";

Tag n12.2.16.0 does not exist in FFmpeg/nv-codec-headers. Fix:

- const NV_CODEC_HEADERS_TAG = "n12.2.16.0";
+ const NV_CODEC_HEADERS_TAG = "n12.2.72.0";

n12.2.72.0 is the latest 12.x release, compatible with FFmpeg n7.1.

Already fixed on my fork's branch (willy-scr:feature/nvenc) — see commit 935216f.

[willy-scr]

@JonnyBurger This PR is ready to merge — all 6 CI checks are passing and mergeable_state is clean.

As noted in remotion-dev/remotion#7733, the rebuilt binary has --enable-encoder=h264_nvenc in the config string but the actual NVENC encoders are missing from libavcodec.so because the nv-codec-headers tag was still broken when the binary was built. Merging this PR first and then rebuilding the binaries should fix that.