feat: add pkg (FreeBSD) and ports (OpenBSD) package manager implementations

pkg implements Manager, VersionQuerier, Cleaner, and FileOwner interfaces
wrapping FreeBSD's pkg(8) CLI. ports implements Manager wrapping OpenBSD's
pkg_add/pkg_delete/pkg_info tools.

Both use build tags (freebsd/openbsd) for real implementations with stub
files for other platforms. Includes parser tests for all output formats.

pkg/pkg_test.go

@@ -0,0 +1,141 @@
+package pkg
+
+import (
+	"testing"
+
+	"github.com/gogrlx/snack"
+)
+
+func TestParseQuery(t *testing.T) {
+	input := "nginx\t1.24.0\tRobust and small WWW server\ncurl\t8.5.0\tCommand line tool for transferring data\n"
+	pkgs := parseQuery(input)
+	if len(pkgs) != 2 {
+		t.Fatalf("expected 2 packages, got %d", len(pkgs))
+	}
+	if pkgs[0].Name != "nginx" || pkgs[0].Version != "1.24.0" {
+		t.Errorf("unexpected first package: %+v", pkgs[0])
+	}
+	if pkgs[0].Description != "Robust and small WWW server" {
+		t.Errorf("unexpected description: %q", pkgs[0].Description)
+	}
+	if !pkgs[0].Installed {
+		t.Error("expected Installed=true")
+	}
+}
+
+func TestParseSearch(t *testing.T) {
+	input := `nginx-1.24.0                   Robust and small WWW server
+curl-8.5.0                     Command line tool for transferring data
+`
+	pkgs := parseSearch(input)
+	if len(pkgs) != 2 {
+		t.Fatalf("expected 2 packages, got %d", len(pkgs))
+	}
+	if pkgs[0].Name != "nginx" || pkgs[0].Version != "1.24.0" {
+		t.Errorf("unexpected first package: %+v", pkgs[0])
+	}
+	if pkgs[1].Name != "curl" || pkgs[1].Version != "8.5.0" {
+		t.Errorf("unexpected second package: %+v", pkgs[1])
+	}
+}
+
+func TestParseInfo(t *testing.T) {
+	input := `Name           : nginx
+Version        : 1.24.0
+Comment        : Robust and small WWW server
+Arch           : FreeBSD:14:amd64
+`
+	pkg := parseInfo(input)
+	if pkg == nil {
+		t.Fatal("expected non-nil package")
+	}
+	if pkg.Name != "nginx" {
+		t.Errorf("expected name 'nginx', got %q", pkg.Name)
+	}
+	if pkg.Version != "1.24.0" {
+		t.Errorf("unexpected version: %q", pkg.Version)
+	}
+	if pkg.Description != "Robust and small WWW server" {
+		t.Errorf("unexpected description: %q", pkg.Description)
+	}
+	if pkg.Arch != "FreeBSD:14:amd64" {
+		t.Errorf("unexpected arch: %q", pkg.Arch)
+	}
+}
+
+func TestParseUpgrades(t *testing.T) {
+	input := `Updating FreeBSD repository catalogue...
+The following 2 package(s) will be affected:
+
+Upgrading nginx: 1.24.0 -> 1.26.0
+Upgrading curl: 8.5.0 -> 8.6.0
+
+Number of packages to be upgraded: 2
+`
+	pkgs := parseUpgrades(input)
+	if len(pkgs) != 2 {
+		t.Fatalf("expected 2 packages, got %d", len(pkgs))
+	}
+	if pkgs[0].Name != "nginx" || pkgs[0].Version != "1.26.0" {
+		t.Errorf("unexpected first package: %+v", pkgs[0])
+	}
+	if pkgs[1].Name != "curl" || pkgs[1].Version != "8.6.0" {
+		t.Errorf("unexpected second package: %+v", pkgs[1])
+	}
+}
+
+func TestParseFileList(t *testing.T) {
+	input := `nginx-1.24.0:
+	/usr/local/sbin/nginx
+	/usr/local/etc/nginx/nginx.conf
+	/usr/local/share/doc/nginx/README
+`
+	files := parseFileList(input)
+	if len(files) != 3 {
+		t.Fatalf("expected 3 files, got %d", len(files))
+	}
+	if files[0] != "/usr/local/sbin/nginx" {
+		t.Errorf("unexpected file: %q", files[0])
+	}
+}
+
+func TestParseOwner(t *testing.T) {
+	input := "/usr/local/sbin/nginx was installed by package nginx-1.24.0\n"
+	name := parseOwner(input)
+	if name != "nginx" {
+		t.Errorf("expected 'nginx', got %q", name)
+	}
+}
+
+func TestSplitNameVersion(t *testing.T) {
+	tests := []struct {
+		input       string
+		wantName    string
+		wantVersion string
+	}{
+		{"nginx-1.24.0", "nginx", "1.24.0"},
+		{"py39-pip-23.1", "py39-pip", "23.1"},
+		{"bash", "bash", ""},
+	}
+	for _, tt := range tests {
+		name, ver := splitNameVersion(tt.input)
+		if name != tt.wantName || ver != tt.wantVersion {
+			t.Errorf("splitNameVersion(%q) = (%q, %q), want (%q, %q)",
+				tt.input, name, ver, tt.wantName, tt.wantVersion)
+		}
+	}
+}
+
+func TestInterfaceCompliance(t *testing.T) {
+	var _ snack.Manager = (*Pkg)(nil)
+	var _ snack.VersionQuerier = (*Pkg)(nil)
+	var _ snack.Cleaner = (*Pkg)(nil)
+	var _ snack.FileOwner = (*Pkg)(nil)
+}
+
+func TestName(t *testing.T) {
+	p := New()
+	if p.Name() != "pkg" {
+		t.Errorf("Name() = %q, want %q", p.Name(), "pkg")
+	}
+}