feat: add dnf and rpm package manager implementations

Implements the dnf sub-package with Manager, VersionQuerier, Holder,
Cleaner, FileOwner, RepoManager, KeyManager, Grouper, and NameNormalizer
interfaces.

Implements the rpm sub-package with Manager, FileOwner, and
NameNormalizer interfaces.

Both follow the existing pattern: exported methods on struct delegate to
unexported functions, _linux.go for real implementations, _other.go with
build-tag stubs, embedded snack.Locker for mutating operations, and
compile-time interface checks.

Includes parser tests for all output formats.

dnf/dnf.go

@@ -1,2 +1,87 @@
-// Package dnf provides Go bindings for DNF (Fedora/RHEL package manager).
+// Package dnf provides Go bindings for the dnf package manager (Fedora/RHEL).
 package dnf
+
+import (
+	"context"
+
+	"github.com/gogrlx/snack"
+)
+
+// DNF wraps the dnf package manager CLI.
+type DNF struct {
+	snack.Locker
+}
+
+// New returns a new DNF manager.
+func New() *DNF {
+	return &DNF{}
+}
+
+// Name returns "dnf".
+func (d *DNF) Name() string { return "dnf" }
+
+// Available reports whether dnf is present on the system.
+func (d *DNF) Available() bool { return available() }
+
+// Install one or more packages.
+func (d *DNF) Install(ctx context.Context, pkgs []snack.Target, opts ...snack.Option) error {
+	d.Lock()
+	defer d.Unlock()
+	return install(ctx, pkgs, opts...)
+}
+
+// Remove one or more packages.
+func (d *DNF) Remove(ctx context.Context, pkgs []snack.Target, opts ...snack.Option) error {
+	d.Lock()
+	defer d.Unlock()
+	return remove(ctx, pkgs, opts...)
+}
+
+// Purge removes packages including configuration files (same as Remove for dnf).
+func (d *DNF) Purge(ctx context.Context, pkgs []snack.Target, opts ...snack.Option) error {
+	d.Lock()
+	defer d.Unlock()
+	return remove(ctx, pkgs, opts...)
+}
+
+// Upgrade all installed packages to their latest versions.
+func (d *DNF) Upgrade(ctx context.Context, opts ...snack.Option) error {
+	d.Lock()
+	defer d.Unlock()
+	return upgrade(ctx, opts...)
+}
+
+// Update refreshes the package index/database.
+func (d *DNF) Update(ctx context.Context) error {
+	d.Lock()
+	defer d.Unlock()
+	return update(ctx)
+}
+
+// List returns all installed packages.
+func (d *DNF) List(ctx context.Context) ([]snack.Package, error) {
+	return list(ctx)
+}
+
+// Search queries the repositories for packages matching the query.
+func (d *DNF) Search(ctx context.Context, query string) ([]snack.Package, error) {
+	return search(ctx, query)
+}
+
+// Info returns details about a specific package.
+func (d *DNF) Info(ctx context.Context, pkg string) (*snack.Package, error) {
+	return info(ctx, pkg)
+}
+
+// IsInstalled reports whether a package is currently installed.
+func (d *DNF) IsInstalled(ctx context.Context, pkg string) (bool, error) {
+	return isInstalled(ctx, pkg)
+}
+
+// Version returns the installed version of a package.
+func (d *DNF) Version(ctx context.Context, pkg string) (string, error) {
+	return version(ctx, pkg)
+}
+
+// Verify interface compliance at compile time.
+var _ snack.Manager = (*DNF)(nil)