Add Docker-based Linux release build for Ubuntu 20.04 compatibility

build-docker-release.sh

@@ -0,0 +1,43 @@
+#!/usr/bin/env bash
+# Build inside Docker container for Ubuntu 20.04 compatibility
+set -eu -o pipefail
+
+cd /hush3
+
+# Clean previous build artifacts that may be from the host
+make clean 2>/dev/null || true
+
+# Clean host-built depends (native binaries won't work in container)
+rm -rf depends/built depends/x86_64-unknown-linux-gnu depends/work
+make -C depends clean 2>/dev/null || true
+
+# Build RandomX for Linux (clean, since host build is different arch/libc)
+cd src/RandomX
+rm -rf build-linux
+mkdir -p build-linux && cd build-linux
+cmake -DARCH=native ..
+make -j$(nproc)
+cd /hush3
+
+# Run the normal build
+./util/build.sh --disable-tests -j$(nproc)
+
+# Package release
+echo "Creating Linux release package..."
+VERSION=$(grep -oP 'define\(_CLIENT_VERSION.*?,\s*\K[0-9]+' configure.ac | head -4 | tr '\n' '.' | sed 's/\.$//')
+VERSION=${VERSION:-3.10.5}
+RELEASE_DIR="release-linux"
+mkdir -p "$RELEASE_DIR"
+
+strip -s src/hushd src/hush-cli src/hush-tx
+cp src/hushd src/hush-cli src/hush-tx "$RELEASE_DIR/"
+cp asmap.dat sapling-spend.params sapling-output.params "$RELEASE_DIR/" 2>/dev/null || true
+cp src/hush-arrakis-chain src/dragonxd src/dragonx-cli "$RELEASE_DIR/"
+
+rm -f "hush-${VERSION}-linux64.zip"
+cd "$RELEASE_DIR"
+zip -9 "../hush-${VERSION}-linux64.zip" *
+cd ..
+
+echo "Release package created: hush-${VERSION}-linux64.zip"
+ls -lh "hush-${VERSION}-linux64.zip"