Add .deb packaging, GitHub Actions CI/CD, and release workflows

- Makefile: add 'deb' and 'release' targets; fix migrate/create syntax
- scripts/build-deb.sh: build .deb with systemd unit, postinst/prerm/postrm
- .github/workflows/ci.yml: go build, test, lint on PR/push to main
- .github/workflows/release.yml: multi-platform build (linux/darwin/windows
  × amd64/arm64), .deb for Linux, tarballs, draft GitHub Release on tag v*
- README.md: add CI/Release badges, Install section with .deb and binary
  release instructions

scripts/build-deb.sh

@@ -0,0 +1,116 @@
+#!/usr/bin/env bash
+# build-deb.sh — Build a .deb package for LlamaLink
+set -euo pipefail
+
+VERSION="${1:-}"
+ARCH="${2:-$(dpkg --print-architecture 2>/dev/null || echo "amd64")}"
+
+if [[ -z "$VERSION" ]]; then
+    VERSION=$(git describe --tags --always --dirty 2>/dev/null || echo "dev")
+    VERSION="${VERSION#v}"
+fi
+
+if ! command -v dpkg-deb &>/dev/null; then
+    echo "Error: dpkg-deb not found. Install with: sudo apt install dpkg" >&2
+    exit 1
+fi
+
+if [[ "$(uname)" != "Linux" ]]; then
+    echo "Error: .deb packages can only be built on Linux." >&2
+    exit 1
+fi
+
+DEB_VERSION="${VERSION}-1"
+BUILD_DIR="dist/deb-build"
+PKG_DIR="${BUILD_DIR}/llamalink-${DEB_VERSION}_${ARCH}"
+
+echo "==> Building llamalink_${DEB_VERSION}_${ARCH}.deb"
+
+rm -rf "$BUILD_DIR"
+mkdir -p "$PKG_DIR"/{DEBIAN,usr/local/bin,etc/llamalink,etc/systemd/system,opt/llamalink/data,var/log/llamalink}
+
+# Binary (must exist)
+if [[ ! -f "bin/llamalink" ]]; then
+    echo "Error: bin/llamalink not found. Run 'make build' first." >&2
+    exit 1
+fi
+cp bin/llamalink "$PKG_DIR/usr/local/bin/"
+chmod 755 "$PKG_DIR/usr/local/bin/llamalink"
+
+# Config template
+cp .env.example "$PKG_DIR/etc/llamalink/env"
+chmod 644 "$PKG_DIR/etc/llamalink/env"
+
+# Systemd unit
+cp deploy/llamalink.service "$PKG_DIR/etc/systemd/system/llamalink.service"
+
+# DEBIAN/control
+cat > "$PKG_DIR/DEBIAN/control" <<EOF
+Package: llamalink
+Version: ${DEB_VERSION}
+Section: net
+Priority: optional
+Architecture: ${ARCH}
+Maintainer: LlamaLink <hello@llamalink.dev>
+Description: API Gateway for local LLM inference via llama.cpp
+ Provides a REST API with API key authentication, rate limiting,
+ and multi-model hot-swap for llama.cpp server instances.
+Homepage: https://github.com/llamalink/llamalink
+Depends: libc6
+EOF
+
+# DEBIAN/conffiles
+echo "/etc/llamalink/env" > "$PKG_DIR/DEBIAN/conffiles"
+
+# DEBIAN/postinst
+cat > "$PKG_DIR/DEBIAN/postinst" <<'POSTINST'
+#!/bin/sh
+set -e
+if [ "$1" = "configure" ]; then
+    if ! id llamalink > /dev/null 2>&1; then
+        useradd --system --no-create-home --shell /usr/sbin/nologin llamalink 2>/dev/null || true
+    fi
+    mkdir -p /opt/llamalink/data /var/log/llamalink
+    chown llamalink:llamalink /opt/llamalink/data /var/log/llamalink 2>/dev/null || true
+    if command -v systemctl >/dev/null 2>&1; then
+        systemctl daemon-reload 2>/dev/null || true
+    fi
+fi
+POSTINST
+chmod 755 "$PKG_DIR/DEBIAN/postinst"
+
+# DEBIAN/prerm
+cat > "$PKG_DIR/DEBIAN/prerm" <<'PRERM'
+#!/bin/sh
+set -e
+if [ "$1" = "remove" ] || [ "$1" = "purge" ]; then
+    if command -v systemctl >/dev/null 2>&1; then
+        systemctl stop llamalink.service 2>/dev/null || true
+        systemctl disable llamalink.service 2>/dev/null || true
+    fi
+fi
+PRERM
+chmod 755 "$PKG_DIR/DEBIAN/prerm"
+
+# DEBIAN/postrm
+cat > "$PKG_DIR/DEBIAN/postrm" <<'POSTRM'
+#!/bin/sh
+set -e
+if [ "$1" = "purge" ]; then
+    rm -rf /opt/llamalink/data /var/log/llamalink
+    if id llamalink > /dev/null 2>&1; then
+        userdel llamalink 2>/dev/null || true
+    fi
+    if command -v systemctl >/dev/null 2>&1; then
+        systemctl daemon-reload 2>/dev/null || true
+    fi
+fi
+POSTRM
+chmod 755 "$PKG_DIR/DEBIAN/postrm"
+
+# Build .deb
+mkdir -p dist
+dpkg-deb --build "$PKG_DIR" "dist/llamalink_${DEB_VERSION}_${ARCH}.deb"
+
+echo "==> Created dist/llamalink_${DEB_VERSION}_${ARCH}.deb"
+rm -rf "$BUILD_DIR"