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.

ports/ports_test.go

@@ -0,0 +1,113 @@
+package ports
+
+import (
+	"testing"
+
+	"github.com/gogrlx/snack"
+)
+
+func TestParseList(t *testing.T) {
+	input := `bash-5.2.21        GNU Bourne Again Shell
+curl-8.5.0         command line tool for transferring data
+python-3.11.7p0    interpreted object-oriented programming language
+`
+	pkgs := parseList(input)
+	if len(pkgs) != 3 {
+		t.Fatalf("expected 3 packages, got %d", len(pkgs))
+	}
+	if pkgs[0].Name != "bash" || pkgs[0].Version != "5.2.21" {
+		t.Errorf("unexpected first package: %+v", pkgs[0])
+	}
+	if pkgs[0].Description != "GNU Bourne Again Shell" {
+		t.Errorf("unexpected description: %q", pkgs[0].Description)
+	}
+	if !pkgs[0].Installed {
+		t.Error("expected Installed=true")
+	}
+	if pkgs[2].Name != "python" || pkgs[2].Version != "3.11.7p0" {
+		t.Errorf("unexpected third package: %+v", pkgs[2])
+	}
+}
+
+func TestParseSearchResults(t *testing.T) {
+	input := `nginx-1.24.0
+nginx-1.25.3
+`
+	pkgs := parseSearchResults(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])
+	}
+}
+
+func TestParseInfoOutput(t *testing.T) {
+	input := `Information for nginx-1.24.0:
+
+Comment:
+robust and small WWW server
+Description:
+nginx is an HTTP and reverse proxy server, a mail proxy server,
+and a generic TCP/UDP proxy server.
+`
+	pkg := parseInfoOutput(input, "nginx-1.24.0")
+	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)
+	}
+}
+
+func TestParseInfoOutputWithComment(t *testing.T) {
+	input := `Information for curl-8.5.0:
+
+Comment: command line tool for transferring data
+Description:
+curl is a tool to transfer data from or to a server.
+`
+	pkg := parseInfoOutput(input, "curl-8.5.0")
+	if pkg == nil {
+		t.Fatal("expected non-nil package")
+	}
+	if pkg.Name != "curl" {
+		t.Errorf("expected name 'curl', got %q", pkg.Name)
+	}
+	if pkg.Description != "command line tool for transferring data" {
+		t.Errorf("unexpected description: %q", pkg.Description)
+	}
+}
+
+func TestSplitNameVersion(t *testing.T) {
+	tests := []struct {
+		input       string
+		wantName    string
+		wantVersion string
+	}{
+		{"nginx-1.24.0", "nginx", "1.24.0"},
+		{"py3-pip-23.1", "py3-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 = (*Ports)(nil)
+}
+
+func TestName(t *testing.T) {
+	p := New()
+	if p.Name() != "ports" {
+		t.Errorf("Name() = %q, want %q", p.Name(), "ports")
+	}
+}