feat(commit): implement commit command parity

internal/homesick/core/core.go

@@ -147,6 +147,24 @@ func (a *App) Push(castle string) error {
 	return runGitWithIO(filepath.Join(a.ReposDir, castle), a.Stdout, a.Stderr, "push")
 }
 
+func (a *App) Commit(castle string, message string) error {
+	if strings.TrimSpace(castle) == "" {
+		castle = "dotfiles"
+	}
+
+	trimmedMessage := strings.TrimSpace(message)
+	if trimmedMessage == "" {
+		return errors.New("commit requires message")
+	}
+
+	castledir := filepath.Join(a.ReposDir, castle)
+	if err := runGitWithIO(castledir, a.Stdout, a.Stderr, "add", "--all"); err != nil {
+		return err
+	}
+
+	return runGitWithIO(castledir, a.Stdout, a.Stderr, "commit", "-m", trimmedMessage)
+}
+
 func (a *App) Link(castle string) error {
 	if strings.TrimSpace(castle) == "" {
 		castle = "dotfiles"