feat: create autonomous Nivora package repository

Maintain a validated cross-distribution package catalog.
Automate upstream updates, isolated builds, diagnostics, and direct publication.
Build the official GitHub Desktop sources for Linux with working OAuth.

tests/test_helper.sh

@@ -0,0 +1,51 @@
+#!/bin/bash
+set -euo pipefail
+
+repo_root="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+temp_dir="$(mktemp -d)"
+
+cleanup() {
+    find "$temp_dir" -mindepth 1 -delete
+    rmdir "$temp_dir"
+}
+trap cleanup EXIT
+
+mkdir -p "${temp_dir}/bin"
+log="${temp_dir}/commands.log"
+
+cat >"${temp_dir}/bin/stplr" <<'EOF'
+#!/bin/bash
+printf 'stplr' >>"$NIVORA_TEST_LOG"
+printf ' %s' "$@" >>"$NIVORA_TEST_LOG"
+printf '\n' >>"$NIVORA_TEST_LOG"
+EOF
+
+cat >"${temp_dir}/bin/test-sudo" <<'EOF'
+#!/bin/bash
+printf 'sudo' >>"$NIVORA_TEST_LOG"
+printf ' %s' "$@" >>"$NIVORA_TEST_LOG"
+printf '\n' >>"$NIVORA_TEST_LOG"
+exec "$@"
+EOF
+
+chmod 0755 "${temp_dir}/bin/"*
+for alias in sli slii sl; do
+    ln -s "$repo_root/nivora-stplr/nivora-stplr" "${temp_dir}/bin/${alias}"
+done
+
+export NIVORA_TEST_LOG="$log"
+export NIVORA_STPLR_SUDO=test-sudo
+export NIVORA_STPLR_QUIET=1
+export PATH="${temp_dir}/bin:${PATH}"
+
+sli --repo nivora parsec --clean
+slii nivora/codex
+
+cat >"${temp_dir}/expected" <<'EOF'
+sudo stplr install nivora/parsec --clean
+stplr install nivora/parsec --clean
+stplr info nivora/codex
+EOF
+
+diff -u "${temp_dir}/expected" "$log"
+echo 'OK: Nivora helper'