Implement collect CLI tool

- Add Go implementation with modular architecture
- Support --name flag for exact filename matching
- Support --match flag for directory glob pattern matching
- Create tar.gz and zip archives preserving directory structure
- Handle errors with appropriate exit codes
- Skip files with permission errors gracefully
- Add comprehensive test suite with 11 test cases

collector/collector.go

@@ -0,0 +1,118 @@
+package collector
+
+import (
+	"fmt"
+	"io/fs"
+	"os"
+	"path/filepath"
+	"strings"
+)
+
+// FileEntry represents a file to be archived
+type FileEntry struct {
+	Path     string // Relative path from sourceDir
+	FullPath string // Absolute path for reading
+}
+
+// Collector handles file collection based on a matcher
+type Collector struct {
+	matcher Matcher
+}
+
+// New creates a new collector with the specified matcher
+func New(matcher Matcher) *Collector {
+	return &Collector{
+		matcher: matcher,
+	}
+}
+
+// Collect walks the source directory and collects matching files
+func (c *Collector) Collect(sourceDir string) ([]FileEntry, error) {
+	// Clean and convert to absolute path
+	absSourceDir, err := filepath.Abs(sourceDir)
+	if err != nil {
+		return nil, fmt.Errorf("failed to get absolute path: %w", err)
+	}
+	
+	// Check if source directory exists
+	info, err := os.Stat(absSourceDir)
+	if err != nil {
+		return nil, fmt.Errorf("source directory error: %w", err)
+	}
+	if !info.IsDir() {
+		return nil, fmt.Errorf("source path is not a directory: %s", sourceDir)
+	}
+	
+	var files []FileEntry
+	
+	err = filepath.WalkDir(absSourceDir, func(path string, d fs.DirEntry, err error) error {
+		if err != nil {
+			// Log permission errors but continue walking
+			if os.IsPermission(err) {
+				fmt.Fprintf(os.Stderr, "Warning: Permission denied: %s\n", path)
+				return nil
+			}
+			return err
+		}
+		
+		// Get file info
+		info, err := d.Info()
+		if err != nil {
+			if os.IsPermission(err) {
+				fmt.Fprintf(os.Stderr, "Warning: Cannot stat file: %s\n", path)
+				return nil
+			}
+			return err
+		}
+		
+		// Skip symlinks
+		if info.Mode()&os.ModeSymlink != 0 {
+			return nil
+		}
+		
+		// Check if this file should be included
+		if c.matcher.ShouldInclude(path, info) {
+			// Calculate relative path from source directory
+			relPath, err := filepath.Rel(absSourceDir, path)
+			if err != nil {
+				return fmt.Errorf("failed to get relative path: %w", err)
+			}
+			
+			// Clean the relative path to ensure consistent formatting
+			relPath = filepath.ToSlash(relPath)
+			
+			files = append(files, FileEntry{
+				Path:     relPath,
+				FullPath: path,
+			})
+		}
+		
+		return nil
+	})
+	
+	if err != nil {
+		return nil, fmt.Errorf("walk error: %w", err)
+	}
+	
+	// Check if any files were found
+	if len(files) == 0 {
+		return nil, fmt.Errorf("no files found matching criteria")
+	}
+	
+	return files, nil
+}
+
+// GetArchiveFormat determines the archive format from the filename
+func GetArchiveFormat(filename string) string {
+	lower := strings.ToLower(filename)
+	
+	if strings.HasSuffix(lower, ".tar.gz") || strings.HasSuffix(lower, ".tgz") {
+		return "tar.gz"
+	}
+	
+	if strings.HasSuffix(lower, ".zip") {
+		return "zip"
+	}
+	
+	return ""
+}