Add ETA estimation to cluster backup/restore operations

- Created internal/progress/estimator.go with ETAEstimator component
- Tracks elapsed time and estimates remaining time based on progress
- Enhanced Spinner and LineByLine indicators to display ETA info
- Integrated into BackupCluster and RestoreCluster functions
- Display format: 'Operation | X/Y (Z%) | Elapsed: Xm | ETA: ~Ym remaining'
- Preserves spinner animation while showing progress/time estimates
- Quick Win approach: no historical data storage, just current operation tracking

bin/README.md

@@ -4,8 +4,8 @@ This directory contains pre-compiled binaries for the DB Backup Tool across mult
 
 ## Build Information
 - **Version**: 1.1.0
-- **Build Time**: 2025-11-06_08:16:58_UTC
-- **Git Commit**: 26ad1dc
+- **Build Time**: 2025-11-07_13:27:44_UTC
+- **Git Commit**: ebb77fb
 
 ## Recent Updates (v1.1.0)
 - ✅ Fixed TUI progress display with line-by-line output