fix: switch to build-package.sh for .deb builds

* fix: switch to build-package.sh for .deb builds

Replace dpkg-buildpackage with scripts/build-package.sh using
dpkg-deb --build approach. This bypasses the dpkg-buildpackage
subprocess chain (dh → make → debian/rules → cargo) which
does not inherit the rustup environment (RUSTUP_HOME, CARGO_HOME,
default toolchain) from GitHub Actions.

Same approach as Linux-Patch-Manager which passes CI.

- Add scripts/build-package.sh (modeled after Manager)
- Add Version and Installed-Size to debian/control
- Update CI workflow to use build-package.sh
- Fix release files path (project root, not ../)

* fix: extract only binary package paragraph from debian/control

dpkg-deb --build expects a single control paragraph starting
with Package: field. The debian/control file has two paragraphs
(source + binary). The awk command extracts only the binary
package paragraph to avoid dpkg-deb parse errors.

* fix: generate DEBIAN/control from scratch in build-package.sh

dpkg-deb --build is fundamentally incompatible with debian/control
which uses dpkg-buildpackage substitution variables like
${shlibs:Depends} and ${misc:Depends}. Generate a clean control
file from scratch in the script to eliminate all incompatibilities.

- No substitution variables
- No source paragraph
- No Build-Depends
- Homepage points to GitHub
- Installed-Size calculated before control file generation

---------

Co-authored-by: git-echo <git-echo@moon-dragon.us>

scripts/build-package.sh

@@ -0,0 +1,143 @@
+#!/usr/bin/env bash
+# =============================================================================
+# Linux Patch API — Build .deb Package for Ubuntu 24.04
+# =============================================================================
+# Produces: linux-patch-api_<version>-1_amd64.deb
+# Prerequisites:
+#   - Rust toolchain (cargo, rustc >= 1.75)
+#   - dpkg-deb
+# =============================================================================
+
+set -euo pipefail
+
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+CYAN='\033[0;36m'
+NC='\033[0m'
+
+info()  { echo -e "${GREEN}[INFO]${NC}  $*"; }
+warn()  { echo -e "${YELLOW}[WARN]${NC} $*"; }
+error() { echo -e "${RED}[ERROR]${NC} $*" >&2; exit 1; }
+
+PROJECT_ROOT="$(cd "$(dirname "${BASH_SOURCE[0]}")/.." && pwd)"
+VERSION="1.2.0"
+RELEASE="1"
+PKG_NAME="linux-patch-api"
+DEB_NAME="${PKG_NAME}_${VERSION}-${RELEASE}_amd64.deb"
+BUILD_DIR="${PROJECT_ROOT}/package-build"
+
+info "=== Linux Patch API — Package Build ==="
+info "Version: ${VERSION}-${RELEASE}"
+info "Target:  Ubuntu 24.04 (noble) amd64"
+echo
+
+# ---------------------------------------------------------------------------
+# 1. Build Rust binary (release mode)
+# ---------------------------------------------------------------------------
+info "Step 1/4: Building Rust binary (release mode)..."
+cd "${PROJECT_ROOT}"
+cargo build --release 2>&1 | tail -5
+
+# Verify binary exists
+[[ -f "${PROJECT_ROOT}/target/release/linux-patch-api" ]] || error "linux-patch-api not found in target/release/"
+info "Rust binary built successfully."
+
+# Strip debug symbols for smaller package
+strip "${PROJECT_ROOT}/target/release/linux-patch-api" 2>/dev/null || warn "strip failed (may already be stripped)"
+info "Binary stripped."
+
+# ---------------------------------------------------------------------------
+# 2. Assemble package directory structure
+# ---------------------------------------------------------------------------
+info "Step 2/4: Assembling package structure..."
+rm -rf "${BUILD_DIR}"
+mkdir -p "${BUILD_DIR}/DEBIAN"
+mkdir -p "${BUILD_DIR}/usr/bin"
+mkdir -p "${BUILD_DIR}/etc/linux_patch_api"
+mkdir -p "${BUILD_DIR}/etc/linux_patch_api/certs"
+mkdir -p "${BUILD_DIR}/lib/systemd/system"
+mkdir -p "${BUILD_DIR}/var/log/linux_patch_api"
+mkdir -p "${BUILD_DIR}/var/lib/linux_patch_api"
+
+# Binary
+cp "${PROJECT_ROOT}/target/release/linux-patch-api" "${BUILD_DIR}/usr/bin/linux-patch-api"
+chmod 755 "${BUILD_DIR}/usr/bin/linux-patch-api"
+
+# Systemd service
+cp "${PROJECT_ROOT}/configs/linux-patch-api.service" "${BUILD_DIR}/lib/systemd/system/"
+
+# Configuration files
+cp "${PROJECT_ROOT}/configs/config.yaml.example" "${BUILD_DIR}/etc/linux_patch_api/config.yaml"
+cp "${PROJECT_ROOT}/configs/whitelist.yaml.example" "${BUILD_DIR}/etc/linux_patch_api/whitelist.yaml"
+
+# Calculate installed size BEFORE generating control file
+INSTALLED_SIZE=$(du -sk "${BUILD_DIR}" | cut -f1)
+
+# Generate DEBIAN/control from scratch for dpkg-deb --build
+# (debian/control uses dpkg-buildpackage substitution variables like
+#  ${shlibs:Depends} that dpkg-deb cannot resolve)
+cat > "${BUILD_DIR}/DEBIAN/control" <<EOF
+Package: linux-patch-api
+Version: ${VERSION}-${RELEASE}
+Architecture: amd64
+Maintainer: Echo <echo@moon-dragon.us>
+Installed-Size: ${INSTALLED_SIZE}
+Depends: systemd, libsystemd0
+Section: admin
+Priority: optional
+Homepage: https://github.com/Draco-Lunaris/Linux-Patch-Api
+Description: Secure remote package management API for Linux systems
+ Linux Patch API provides a secure, mTLS-authenticated REST API for
+ remote package management operations including package installation
+ and removal, security patch application, system health monitoring,
+ and job queue management with WebSocket status streaming.
+EOF
+
+# Conffiles
+cat > "${BUILD_DIR}/DEBIAN/conffiles" << 'EOF'
+/etc/linux_patch_api/config.yaml
+/etc/linux_patch_api/whitelist.yaml
+EOF
+
+# Maintainer scripts
+cp "${PROJECT_ROOT}/debian/postinst" "${BUILD_DIR}/DEBIAN/postinst"
+cp "${PROJECT_ROOT}/debian/prerm" "${BUILD_DIR}/DEBIAN/prerm"
+cp "${PROJECT_ROOT}/debian/postrm" "${BUILD_DIR}/DEBIAN/postrm"
+chmod 755 "${BUILD_DIR}/DEBIAN/postinst" "${BUILD_DIR}/DEBIAN/prerm" "${BUILD_DIR}/DEBIAN/postrm"
+
+info "Package structure assembled (${INSTALLED_SIZE} KB)."
+
+# ---------------------------------------------------------------------------
+# 3. Build .deb package
+# ---------------------------------------------------------------------------
+info "Step 3/4: Building .deb package..."
+dpkg-deb --build "${BUILD_DIR}" "${PROJECT_ROOT}/${DEB_NAME}"
+info ".deb package created: ${DEB_NAME}"
+
+# ---------------------------------------------------------------------------
+# 4. Verify and summarize
+# ---------------------------------------------------------------------------
+info "Step 4/4: Verifying package..."
+dpkg-deb --info "${PROJECT_ROOT}/${DEB_NAME}"
+echo
+dpkg-deb --contents "${PROJECT_ROOT}/${DEB_NAME}" | head -20 || true
+echo
+
+PKG_SIZE=$(du -h "${PROJECT_ROOT}/${DEB_NAME}" | cut -f1)
+
+info "=== Package Build Complete ==="
+info "Package: ${DEB_NAME}"
+info "Size:   ${PKG_SIZE}"
+echo
+echo -e "${CYAN}Installation instructions:${NC}"
+echo "  1. Copy ${DEB_NAME} to the target Ubuntu 24.04 host"
+echo "  2. Install:  sudo dpkg -i ${DEB_NAME}"
+echo "  3. Or with auto-deps:  sudo apt install ./${DEB_NAME}"
+echo "  4. Configure:  /etc/linux_patch_api/config.yaml"
+echo "  5. Start:  systemctl enable --now linux-patch-api.service"
+echo
+
+# Cleanup build directory
+rm -rf "${BUILD_DIR}"
+info "Build directory cleaned up."