feat(restore): add --parallel-dbs=-1 auto-detection based on CPU/RAM

- Add CalculateOptimalParallel() function to preflight.go
- Calculates optimal workers: min(RAM/3GB, CPU cores), capped at 16
- Reduces parallelism by 50% if memory pressure >80%
- Add -1 flag value for auto-detection mode
- Preflight summary now shows CPU cores and recommended parallel

bin/README.md

@@ -4,8 +4,8 @@ This directory contains pre-compiled binaries for the DB Backup Tool across mult
 
 ## Build Information
 - **Version**: 3.42.50
-- **Build Time**: 2026-01-17_06:48:35_UTC
-- **Git Commit**: dd1db84
+- **Build Time**: 2026-01-17_12:25:20_UTC
+- **Git Commit**: c5be9bc
 
 ## Recent Updates (v1.1.0)
 - ✅ Fixed TUI progress display with line-by-line output