Update metrics tracking and enhance cache eviction strategies

- Added metrics for bytes saved from cache to improve performance insights.
- Updated cache eviction strategies in MemoryFS and DiskFS to include metrics tracking for hits and evictions.
- Enhanced README.md with updated garbage collection algorithm descriptions and recommendations for cache usage.
- Introduced new madviseSequential functionality for improved memory access hints on Unix systems.
- Adjusted validation configuration in examples to better reflect realistic usage scenarios.

go.mod

@@ -8,6 +8,7 @@ require (
 	github.com/rs/zerolog v1.33.0
 	github.com/spf13/cobra v1.8.1
 	golang.org/x/sync v0.16.0
+	golang.org/x/sys v0.12.0
 	gopkg.in/yaml.v3 v3.0.1
 )
 
@@ -16,5 +17,4 @@ require (
 	github.com/mattn/go-colorable v0.1.13 // indirect
 	github.com/mattn/go-isatty v0.0.19 // indirect
 	github.com/spf13/pflag v1.0.5 // indirect
-	golang.org/x/sys v0.12.0 // indirect
 )