feat: add cross-compile and release pipeline

- Enhanced Makefile with cross-compilation for linux/amd64, linux/arm64,
  darwin/arm64, windows/amd64, windows/arm64
- Added GitHub Actions CI workflow for testing on all platforms
- Added GitHub Actions Release workflow triggered by version tags
- Added VERSION file for version tracking
- Added scripts/release.sh for automated release process
- Added Dockerfile for containerized builds
- Added CONTRIBUTING.md with release process documentation
- Added CHANGELOG.md for version tracking
- Updated .gitignore to exclude build artifacts
- Fixed unused variable in cmd/obm/main.go
- Version now injected via ldflags (main.version, main.gitCommit, main.buildTime)

scripts/release.sh

@@ -0,0 +1,118 @@
+#!/bin/bash
+# Release automation script for obm CLI
+# Usage: ./scripts/release.sh <version>
+# Example: ./scripts/release.sh v0.2.0
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/.." && pwd)"
+VERSION_FILE="$PROJECT_ROOT/VERSION"
+
+# Colors
+RED='\033[0;31m'
+GREEN='\033[0;32m'
+YELLOW='\033[1;33m'
+NC='\033[0m' # No Color
+
+log_info() {
+    echo -e "${GREEN}[INFO]${NC} $1"
+}
+
+log_warn() {
+    echo -e "${YELLOW}[WARN]${NC} $1"
+}
+
+log_error() {
+    echo -e "${RED}[ERROR]${NC} $1"
+}
+
+# Validate version argument
+if [ -z "$1" ]; then
+    log_error "Version argument required"
+    echo "Usage: $0 <version>"
+    echo "Example: $0 v0.2.0"
+    exit 1
+fi
+
+NEW_VERSION="$1"
+
+# Strip 'v' prefix if present
+VERSION_NUM="${NEW_VERSION#v}"
+
+# Validate version format (semver)
+if ! [[ "$VERSION_NUM" =~ ^[0-9]+\.[0-9]+\.[0-9]+(-[a-zA-Z0-9.]+)?$ ]]; then
+    log_error "Invalid version format: $NEW_VERSION"
+    echo "Expected format: vX.Y.Z or X.Y.Z (semver)"
+    exit 1
+fi
+
+cd "$PROJECT_ROOT"
+
+# Check for uncommitted changes
+if ! git diff-index --quiet HEAD --; then
+    log_error "Uncommitted changes detected. Please commit or stash first."
+    git status --short
+    exit 1
+fi
+
+# Check for unpushed commits
+LOCAL=$(git rev-parse @)
+REMOTE=$(git rev-parse @{u} 2>/dev/null || echo "")
+
+if [ "$LOCAL" != "$REMOTE" ]; then
+    log_warn "Unpushed commits detected. Push before release?"
+    read -p "Push now? (y/N) " -n 1 -r
+    echo
+    if [[ $REPLY =~ ^[Yy]$ ]]; then
+        git push
+    else
+        log_error "Please push changes before releasing"
+        exit 1
+    fi
+fi
+
+# Run tests
+log_info "Running tests..."
+make test || {
+    log_error "Tests failed. Fix before releasing."
+    exit 1
+}
+
+# Update VERSION file
+log_info "Updating VERSION file to $VERSION_NUM"
+echo "$VERSION_NUM" > "$VERSION_FILE"
+
+# Update version in main.go
+MAIN_GO="$PROJECT_ROOT/cmd/obm/main.go"
+if [ -f "$MAIN_GO" ]; then
+    log_info "Updating version in main.go"
+    sed -i "s/^const version = \".*\"/const version = \"$VERSION_NUM\"/" "$MAIN_GO"
+fi
+
+# Commit version bump
+log_info "Committing version bump"
+git add "$VERSION_FILE" "$MAIN_GO"
+git commit -m "chore: release v$VERSION_NUM"
+
+# Create and push tag
+TAG="v$VERSION_NUM"
+log_info "Creating tag $TAG"
+git tag -a "$TAG" -m "Release $TAG"
+
+log_info "Pushing tag to remote..."
+git push origin "$TAG"
+
+log_info "Release process initiated!"
+echo ""
+echo "Version: $VERSION_NUM"
+echo "Tag: $TAG"
+echo ""
+echo "Next steps:"
+echo "  1. GitHub Actions will build and create the release automatically"
+echo "  2. Monitor at: https://github.com/openboatmobile/obm/actions"
+echo "  3. Draft release will be created at: https://github.com/openboatmobile/obm/releases"
+echo ""
+echo "To manually build binaries:"
+echo "  make cross-compile VERSION=$VERSION_NUM"
+echo ""