chore(workflows): migrate CI workflows from Gitea to GitHub Actions and remove obsolete files

scripts/ci/github-apt-linux-packaging.sh

@@ -0,0 +1,20 @@
+#!/usr/bin/env bash
+# APT packages needed for Linux Electron packaging (AppImage, deb, rpm) on Debian/Ubuntu or in Dockerfile.build (root).
+set -euo pipefail
+
+# shellcheck source=scripts/ci/priv.sh
+. "$(dirname "$0")/priv.sh"
+
+run_priv dpkg --add-architecture i386 || true
+run_priv apt-get update -y
+run_priv apt-get install -y --no-install-recommends \
+    patchelf \
+    libopusfile0 \
+    espeak-ng \
+    zip \
+    rpm \
+    elfutils \
+    fakeroot \
+    file \
+    libc6:i386 \
+    libstdc++6:i386