feat: initial commit of Git Automation CLI

- Add comprehensive Git workflow automation tools
- Include branch management utilities
- Add commit helpers with conventional commit support
- Implement GitHub integration for PR management
- Add configuration management system
- Include comprehensive test coverage
- Add professional documentation and examples

internal/git/git.go

@@ -0,0 +1,125 @@
+package git
+
+import (
+	"bytes"
+	"context"
+	"os/exec"
+	"strings"
+)
+
+func run(ctx context.Context, args ...string) (string, error) {
+	cmd := exec.CommandContext(ctx, "git", args...)
+	var out bytes.Buffer
+	var errb bytes.Buffer
+	cmd.Stdout = &out
+	cmd.Stderr = &errb
+	if err := cmd.Run(); err != nil {
+		if errb.Len() > 0 {
+			return "", fmtError(errb.String())
+		}
+		return "", err
+	}
+	return strings.TrimSpace(out.String()), nil
+}
+
+// Run is a public version of run for use in other packages
+func Run(ctx context.Context, args ...string) (string, error) {
+	return run(ctx, args...)
+}
+
+func Fetch(ctx context.Context) error {
+	_, err := run(ctx, "fetch", "--prune")
+	return err
+}
+
+func RebaseOntoTracking(ctx context.Context) error {
+	branch, err := CurrentBranch(ctx)
+	if err != nil {
+		return err
+	}
+	up, err := UpstreamFor(ctx, branch)
+	if err != nil {
+		return err
+	}
+	_, err = run(ctx, "rebase", up)
+	return err
+}
+
+func PushCurrent(ctx context.Context, forceWithLease bool) error {
+	args := []string{"push"}
+	if forceWithLease {
+		args = append(args, "--force-with-lease")
+	}
+	args = append(args, "--set-upstream", "origin", "HEAD")
+	_, err := run(ctx, args...)
+	return err
+}
+
+func LocalBranches(ctx context.Context) ([]string, error) {
+	out, err := run(ctx, "branch", "--format=%(refname:short)")
+	if err != nil {
+		return nil, err
+	}
+	if out == "" {
+		return nil, nil
+	}
+	return strings.Split(out, "\n"), nil
+}
+
+func DeleteBranch(ctx context.Context, name string) error {
+	_, err := run(ctx, "branch", "-D", name)
+	return err
+}
+
+func CurrentBranch(ctx context.Context) (string, error) {
+	return run(ctx, "rev-parse", "--abbrev-ref", "HEAD")
+}
+
+func UpstreamFor(ctx context.Context, branch string) (string, error) {
+	return run(ctx, "rev-parse", "--abbrev-ref", branch+"@{upstream}")
+}
+
+func CreateBranch(ctx context.Context, name string) error {
+	_, err := run(ctx, "checkout", "-b", name)
+	return err
+}
+
+func SwitchBranch(ctx context.Context, name string) error {
+	_, err := run(ctx, "checkout", name)
+	return err
+}
+
+func IsCleanWorkingDir(ctx context.Context) (bool, error) {
+	out, err := run(ctx, "status", "--porcelain")
+	if err != nil {
+		return false, err
+	}
+	return out == "", nil
+}
+
+func AddAll(ctx context.Context) error {
+	_, err := run(ctx, "add", "-A")
+	return err
+}
+
+func Commit(ctx context.Context, message string) error {
+	_, err := run(ctx, "commit", "-m", message)
+	return err
+}
+
+func fmtError(s string) error {
+	return &gitError{msg: strings.TrimSpace(s)}
+}
+
+type gitError struct {
+	msg string
+}
+
+func (e *gitError) Error() string {
+	return e.msg
+}
+
+// GetRemoteURL returns the URL of the specified remote
+func GetRemoteURL(ctx context.Context, remote string) (string, error) {
+	return run(ctx, "remote", "get-url", remote)
+}