The native scripts picked an NDK host tag for macOS as well, but
ci/setup-toolchain.sh provisions nothing outside Linux x86_64 and no
pipeline exercises the other branch. Fail with the message setup already
gives instead of naming a toolchain nobody can obtain here.

The armeabi-v7a and x86 cases were never reachable either: ABIS ships
arm64-v8a and x86_64, and ci/verify-apk.sh has no machine check for the
other two, so adding one to ABIS failed the build it was meant to
enable. Record what a new ABI actually costs instead of inviting a
one-line edit that cannot work.

Update rsync to 3.5.0 and Go to 1.26.6. Bound SSH handshakes, pin
host-key types, and build 16 KB-aligned hardened executables.

The NDK names its prebuilt toolchain directory after the build host,
not the target. Hardcoding linux-x86_64 broke rsync/build.sh and
rsh/build.sh on macOS, which ships the toolchain under darwin-x86_64
(x86_64 binaries, run under Rosetta on Apple Silicon). Detect the
host with uname and fail loud on anything else.

Link: https://codeberg.org/0xlena/rsend/pulls/1

A small Android app for one-way folder backup, a KISS alternative to
Syncthing. It bundles rsync (built from pinned source via the NDK) and
a pure-Go SSH transport, both shipped in the APK as lib*.so and run from
the native library directory.

rsend pins the host key, stores the ed25519 identity Keystore-encrypted,
pushes each folder additively or as a mirror, and runs on demand or on a
WiFi-only schedule. The build is self-contained and reproducible: make
setup provisions the toolchain, make builds rsync, rsh, and the APK.