The release carried nothing installable on a router. Build the OpenWrt package
in the SDK for the four architectures that cover most consumer hardware:
mipsel_24kc ramips, MediaTek MT7620/MT7621
mips_24kc ath79, Atheros/QCA
arm_cortex-a7_neon-vfpv4 ipq40xx
aarch64_cortex-a53 mediatek filogic and similar
Linking against the distribution's libraries rather than building static keeps
the package near 100kB and gives it TLS and PCRE support.
The SDK file name carries the toolchain flavour and differs between targets -
ipq40xx is musl_eabi where the others are musl - so it is taken from the
directory listing instead of being assembled from the target name.
The package is built from the checked out tree rather than the published
release archive: the workflow runs when a release is created, and depending on
GitHub having generated that archive already would be a race.
opkg verifies the signature of a feed index and never of a package file, so
the packages are published with checksums and a signature over them, in the
same shape as the other artifacts, and are not signed in any opkg specific
way.
