feat: add interactive wizard, contextual errors, and code improvements

- Add interactive configuration wizard with auto-detection and multi-format export
- Implement contextual error system with 14 error codes and actionable suggestions
- Add centralized progress indicators with consistent theming
- Fix all cyclomatic complexity issues (8 functions refactored)
- Eliminate code duplication with centralized utilities and error handling
- Add comprehensive test coverage for all new components
- Update TODO.md with completed tasks and accurate completion dates

internal/progress.go

@@ -0,0 +1,50 @@
+// Package internal provides progress bar utilities for the gh-action-readme tool.
+package internal
+
+import (
+	"github.com/schollz/progressbar/v3"
+)
+
+// ProgressBarManager handles progress bar creation and management.
+type ProgressBarManager struct {
+	quiet bool
+}
+
+// NewProgressBarManager creates a new progress bar manager.
+func NewProgressBarManager(quiet bool) *ProgressBarManager {
+	return &ProgressBarManager{
+		quiet: quiet,
+	}
+}
+
+// CreateProgressBar creates a progress bar with standardized options.
+func (pm *ProgressBarManager) CreateProgressBar(description string, total int) *progressbar.ProgressBar {
+	if total <= 1 || pm.quiet {
+		return nil
+	}
+
+	return progressbar.NewOptions(total,
+		progressbar.OptionSetDescription(description),
+		progressbar.OptionSetWidth(50),
+		progressbar.OptionShowCount(),
+		progressbar.OptionShowIts(),
+		progressbar.OptionSetTheme(progressbar.Theme{
+			Saucer:        "=",
+			SaucerHead:    ">",
+			SaucerPadding: " ",
+			BarStart:      "[",
+			BarEnd:        "]",
+		}))
+}
+
+// CreateProgressBarForFiles creates a progress bar for processing multiple files.
+func (pm *ProgressBarManager) CreateProgressBarForFiles(description string, files []string) *progressbar.ProgressBar {
+	return pm.CreateProgressBar(description, len(files))
+}
+
+// FinishProgressBar completes the progress bar display.
+func (pm *ProgressBarManager) FinishProgressBar(bar *progressbar.ProgressBar) {
+	if bar != nil {
+		_ = bar.Finish()
+	}
+}