fix(media): use LGPL FFmpeg build

Co-authored-by: Codex <noreply@openai.com>

scripts/build-ffmpeg-lgpl.sh

@@ -0,0 +1,58 @@
+#!/bin/sh
+
+# Build the relay's FFmpeg/ffprobe toolchain without GPL or non-redistributable
+# components. The only external codec enabled here is BSD-licensed OpenH264;
+# all other media support comes from FFmpeg's LGPL implementation.
+
+set -eu
+
+: "${FFMPEG_VERSION:=7.1.5}"
+: "${FFMPEG_SHA256:=de668509caf9e35e3cd162473441fdb29538c6d96ed080292b3cf9e6fc5d558f}"
+: "${FFMPEG_PREFIX:=/opt/ffmpeg}"
+
+archive="/tmp/ffmpeg-${FFMPEG_VERSION}.tar.xz"
+source_dir="/tmp/ffmpeg-${FFMPEG_VERSION}"
+
+curl --fail --location --silent --show-error \
+  "https://ffmpeg.org/releases/ffmpeg-${FFMPEG_VERSION}.tar.xz" \
+  --output "${archive}"
+echo "${FFMPEG_SHA256}  ${archive}" | sha256sum --check --strict
+tar --extract --file "${archive}" --directory /tmp
+
+cd "${source_dir}"
+./configure \
+  --prefix="${FFMPEG_PREFIX}" \
+  --disable-autodetect \
+  --disable-debug \
+  --disable-doc \
+  --disable-ffplay \
+  --disable-network \
+  --disable-static \
+  --enable-libopenh264 \
+  --enable-shared \
+  --extra-ldflags="-Wl,-rpath,${FFMPEG_PREFIX}/lib" \
+  --enable-zlib
+
+make --jobs="$(getconf _NPROCESSORS_ONLN)"
+make install
+
+license_dir="${FFMPEG_PREFIX}/share/licenses/ffmpeg"
+openh264_license_dir="${FFMPEG_PREFIX}/share/licenses/openh264"
+source_archive_dir="${FFMPEG_PREFIX}/share/source/ffmpeg"
+mkdir -p "${license_dir}" "${openh264_license_dir}" "${source_archive_dir}"
+cp COPYING.LGPLv2.1 LICENSE.md "${license_dir}/"
+cp /usr/share/doc/libopenh264-dev/copyright "${openh264_license_dir}/"
+cp "${archive}" "${source_archive_dir}/"
+
+"${FFMPEG_PREFIX}/bin/ffmpeg" -hide_banner -buildconf \
+  > "${source_archive_dir}/build-configuration.txt" 2>&1
+
+if grep -q -- '--enable-gpl\|--enable-nonfree' \
+  "${source_archive_dir}/build-configuration.txt"; then
+  echo "Refusing to package a GPL or non-redistributable FFmpeg build" >&2
+  exit 1
+fi
+
+"${FFMPEG_PREFIX}/bin/ffmpeg" -hide_banner -encoders 2>&1 \
+  | grep -q 'libopenh264'
+"${FFMPEG_PREFIX}/bin/ffprobe" -hide_banner -version >/dev/null