refactor: migrate to gitea actions

ci/build-rust.sh

@@ -0,0 +1,13 @@
+#!/bin/sh
+set -eu
+
+: "${SCCACHE_REDIS_ENDPOINT:?Set the persistent sccache Redis endpoint}"
+: "${JOBS:=8}"
+case "$JOBS" in ''|*[!0-9]*|0) echo 'JOBS must be a positive integer' >&2; exit 1 ;; esac
+
+sccache --start-server
+trap 'sccache --show-stats; sccache --stop-server' EXIT
+sccache --zero-stats
+# Preserve Jenkins' serial diagnostic retry. Both attempts use the same cache.
+make package/rust/host/compile -j"$JOBS" || make package/rust/host/compile -j1 V=sc
+rm -rf build_dir/host/rustc-*/rustc-*/build dl/rustc-*.tar.*