fix(packaging): install punktfunk-host on Ubuntu 24.04 LTS via a noble builder that bundles FFmpeg 8

The host .deb was built on the Ubuntu 26.04 rust-ci image, so dpkg-shlibdeps
baked in `Depends: libavcodec62` (FFmpeg 8) and a glibc-2.41 floor — making it
uninstallable on Ubuntu 24.04 LTS (FFmpeg 6.1 / libavcodec60, glibc 2.39; apt
reports the deps as "too recent"). The source floor (ffmpeg-next 8, libavcodec
>=61 APIs) means a straight 24.04 rebuild would fail too.

Build the host on Ubuntu 24.04 instead — lowering the glibc floor to 2.39 so one
binary runs on 24.04 -> 26.04 — and bundle a from-source LGPL FFmpeg 8 into the
package so it no longer depends on the distro libav*. Everything else the host
links is soname-compatible on 24.04 (opus is vendored via cmake; NVENC/libcuda
are dlopen-only, never link-time), and the only FFmpeg encoders used are
*_nvenc / *_vaapi (software H.264 fallback is the BSD-2 openh264 crate, not
FFmpeg libx264), so an LGPL build keeps the bundle license-clean.

- ci/rust-ci-noble.Dockerfile (new): ubuntu:24.04 builder; nv-codec-headers +
  FFmpeg 8 (--enable-nvenc --enable-vaapi, shared) -> /opt/ffmpeg; PKG_CONFIG_PATH.
- packaging/debian/build-deb.sh: BUNDLE_FFMPEG=1 copies libav*/libsw*/libpostproc
  into /usr/lib/punktfunk-host, patchelf-sets the rpath ($ORIGIN per-lib + binary
  --force-rpath), feeds them to dpkg-shlibdeps (captures libva2/libdrm2), and drops
  the libav* sonames from Depends. Normal (non-bundle) path unchanged.
- .gitea/workflows/deb.yml: split into build-publish (client/web/scripting on the
  26.04 image) and build-publish-host (noble image, BUNDLE_FFMPEG=1); parallel,
  identical version step, same apt distribution -> one universal host .deb.
- .gitea/workflows/docker.yml: build+push punktfunk-rust-ci-noble.
- packaging/debian/README.md: document the 24.04 LTS path + bundled local build.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

ci/rust-ci-noble.Dockerfile

@@ -0,0 +1,85 @@
+# LTS builder for the punktfunk HOST .deb — Ubuntu 24.04 (noble), the current Ubuntu LTS.
+#
+# WHY THIS EXISTS (see packaging/debian/README.md → "Ubuntu 24.04 LTS"):
+# The default builder (ci/rust-ci.Dockerfile) is Ubuntu 26.04, so the host .deb it produces bakes
+# in a glibc 2.41 floor and a hard `Depends: libavcodec62, …` (FFmpeg 8). Ubuntu 24.04 LTS ships
+# glibc 2.39 and FFmpeg 6.1 (libavcodec60), so that .deb is uninstallable there — apt reports the
+# deps as "too recent". Building the host on 24.04 instead lowers the glibc floor to 2.39 (the
+# binary then runs on 24.04 → 26.04), and the ONE library 24.04 is too old for — FFmpeg — is built
+# from source here and BUNDLED into the .deb (packaging/debian/build-deb.sh, BUNDLE_FFMPEG=1), so
+# the package no longer depends on the distro's libav* at all. Everything else the host links
+# (PipeWire, Wayland, xkbcommon, GL/EGL/GBM, Vulkan; opus is vendored via cmake) is soname-compatible
+# on 24.04, so this ONE universal host .deb replaces the 26.04-built one for every Ubuntu user.
+#
+# libcuda is deliberately NOT provided: the host dlopen's libcuda.so.1 at runtime (pf-zerocopy /
+# pf-encode) and never link-imports it, so — unlike the full-workspace rust-ci image, which builds
+# tests that DO link a cuda stub — this host-only build needs no NVIDIA driver package. NVENC/EGL
+# come from whatever driver the target runs, out of band.
+#
+# Rebuilt+pushed by .gitea/workflows/docker.yml (matrix: punktfunk-rust-ci-noble); consumed by the
+# `build-publish-host` job in .gitea/workflows/deb.yml. Bootstrap: like rust-ci, the first deb.yml
+# run after this image is added uses the image from a PRIOR docker.yml push — seed it once manually
+# (docker build -f ci/rust-ci-noble.Dockerfile -t … ci && docker push) before the host job can run.
+FROM ubuntu:24.04
+ENV DEBIAN_FRONTEND=noninteractive
+
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    # toolchain + bindgen; nodejs runs the JS actions (checkout/cache); unzip for the rustup installer's deps
+    build-essential clang libclang-dev pkg-config cmake git curl ca-certificates nodejs unzip \
+    # .deb assembly: dpkg-shlibdeps/dpkg-deb; patchelf repoints the binary's rpath at the bundled FFmpeg
+    dpkg-dev patchelf \
+    # FFmpeg 8 build deps: nasm (asm), VAAPI (libva/libdrm) so the built libav* keep the AMD/Intel
+    # encode backend the host auto-selects; zlib (libavformat). NVENC needs only headers (below), dlopen'd.
+    nasm libva-dev libdrm-dev zlib1g-dev \
+    # host link deps present on 24.04 with sonames compatible up to 26.04
+    libpipewire-0.3-dev libwayland-dev libxkbcommon-dev \
+    libgl-dev libegl-dev libgbm-dev libvulkan-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+# --- FFmpeg 8 from source -> /opt/ffmpeg (shared libs + .pc files) ----------------------------------
+# libavcodec.so.62, matching the 26.04 line's soname so the host behaves identically. This is an
+# LGPL build (no --enable-gpl / --enable-nonfree) so bundling the .so's into an MIT/Apache .deb stays
+# license-clean — LGPL's relink clause is satisfied by dynamic linking, and the only encoders the host
+# calls (h264/hevc/av1 _nvenc + _vaapi, plus scale_vaapi/hwmap filters; software H.264 fallback is the
+# BSD-2 openh264 crate, NOT FFmpeg libx264) are all LGPL-compatible.
+# Sourced from the official FFmpeg GitHub mirror by release tag, NOT ffmpeg.org: the CI build network
+# can't reach ffmpeg.org (curl times out) but reaches github.com fine. The `nX.Y` tag pins the version
+# (n8.0 -> libavcodec 62); bump it to move FFmpeg. Immutable-tag clone, so no separate checksum needed.
+ARG FFMPEG_TAG=n8.0
+# nv-codec-headers must MATCH the FFmpeg version: its `master` is NVENC SDK 13, which renamed
+# NV_ENC_CLOCK_TIMESTAMP_SET.countingType -> countingTypeLSB and won't compile against FFmpeg 8.0's
+# nvenc.c. Pin the last SDK-12 tag (has the field FFmpeg 8.0 expects). Bump alongside FFMPEG_TAG.
+ARG NVHDR_TAG=n12.2.72.0
+RUN set -eux; \
+    # nv-codec-headers: the NVENC/NVDEC headers FFmpeg's --enable-nvenc needs (headers only, no lib —
+    # the driver is dlopen'd at runtime). Installs ffnvcodec.pc under /usr/local/lib/pkgconfig.
+    git clone --depth 1 --branch "$NVHDR_TAG" https://github.com/FFmpeg/nv-codec-headers.git /tmp/nvhdr; \
+    make -C /tmp/nvhdr install PREFIX=/usr/local; \
+    git clone --depth 1 --branch "$FFMPEG_TAG" https://github.com/FFmpeg/FFmpeg.git /tmp/ffmpeg; \
+    cd /tmp/ffmpeg; \
+    PKG_CONFIG_PATH=/usr/local/lib/pkgconfig ./configure \
+      --prefix=/opt/ffmpeg \
+      --enable-shared --disable-static \
+      --disable-doc --disable-programs --disable-debug \
+      --enable-nvenc --enable-vaapi \
+      --extra-cflags=-I/usr/local/include --extra-ldflags=-L/usr/local/lib; \
+    make -j"$(nproc)"; make install; \
+    cd /; rm -rf /tmp/ffmpeg /tmp/nvhdr; \
+    # sanity: the soname we expect to bundle (libavcodec.so.62 on FFmpeg 8)
+    test -e /opt/ffmpeg/lib/libavcodec.so.62
+
+# ffmpeg-sys-next discovers FFmpeg via pkg-config; point it at the bundled build. PKG_CONFIG_PATH is
+# PREPENDED to pkg-config's default dirs (not a replacement — that's PKG_CONFIG_LIBDIR), so PipeWire /
+# Wayland / libva / … still resolve from the system. FFMPEG_PREFIX is read by build-deb.sh's bundler.
+ENV PKG_CONFIG_PATH=/opt/ffmpeg/lib/pkgconfig \
+    FFMPEG_PREFIX=/opt/ffmpeg
+
+# Toolchain shared across CI users (jobs may run as different uids).
+ENV RUSTUP_HOME=/usr/local/rustup \
+    CARGO_HOME=/usr/local/cargo \
+    PATH=/usr/local/cargo/bin:$PATH
+RUN curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs \
+    | sh -s -- -y --no-modify-path --profile minimal \
+        --component rustfmt,clippy \
+    && chmod -R a+w "$RUSTUP_HOME" "$CARGO_HOME" \
+    && rustc --version && cargo clippy --version && cargo fmt --version