feat(platform): add Reinstall helpers to Pacman and Yay

internal/platform/pacman_test.go

@@ -39,6 +39,27 @@ func TestPacmanInstallShellsOutCorrectly(t *testing.T) {
 	}
 }
 
+func TestPacmanReinstall(t *testing.T) {
+	r := &fakeRunner{}
+	p := NewPacman(r)
+	if err := p.Reinstall(context.Background(), []string{"git", "curl"}); err != nil {
+		t.Fatal(err)
+	}
+	if len(r.runCalls) != 1 {
+		t.Fatalf("run calls = %d", len(r.runCalls))
+	}
+	got := r.runCalls[0]
+	want := []string{"sudo", "pacman", "-S", "--noconfirm", "git", "curl"}
+	if !reflect.DeepEqual(got, want) {
+		t.Fatalf("args = %v, want %v", got, want)
+	}
+	for _, a := range got {
+		if a == "--needed" {
+			t.Fatalf("Reinstall must not pass --needed; got %v", got)
+		}
+	}
+}
+
 func TestPacmanInstallEmptyIsNoop(t *testing.T) {
 	r := &fakeRunner{}
 	p := NewPacman(r)