feat(packages): implement PlanForce to reinstall all packages

Adds Reinstall method to PackageManager and AURHelper interfaces
so modules can invoke the concrete Reinstall helpers behind the
interface. *Pacman and *Yay already satisfy it.

internal/platform/aur.go

@@ -11,6 +11,7 @@ import (
 type AURHelper interface {
 	EnsureInstalled(ctx context.Context) error
 	Install(ctx context.Context, pkgs []string) error
+	Reinstall(ctx context.Context, pkgs []string) error
 }
 
 type Yay struct {