v3.42.34: Add spf13/afero for filesystem abstraction

- New internal/fs package for testable filesystem operations
- In-memory filesystem support for unit testing without disk I/O
- Swappable global FS: SetFS(afero.NewMemMapFs())
- Wrapper functions: ReadFile, WriteFile, Mkdir, Walk, Glob, etc.
- Testing helpers: WithMemFs(), SetupTestDir()
- Comprehensive test suite demonstrating usage
- Upgraded afero from v1.10.0 to v1.15.0

bin/README.md

@@ -3,9 +3,9 @@
 This directory contains pre-compiled binaries for the DB Backup Tool across multiple platforms and architectures.
 
 ## Build Information
-- **Version**: 3.42.32
-- **Build Time**: 2026-01-14_15:13:08_UTC
-- **Git Commit**: 6a24ee3
+- **Version**: 3.42.33
+- **Build Time**: 2026-01-14_15:19:48_UTC
+- **Git Commit**: 4e09066
 
 ## Recent Updates (v1.1.0)
 - ✅ Fixed TUI progress display with line-by-line output