Refactor configuration management and enhance build process

- Introduced a YAML-based configuration system, allowing for automatic generation of a default `config.yaml` file.
- Updated the application to load configuration settings from the YAML file, improving flexibility and ease of use.
- Added a Makefile to streamline development tasks, including running the application, testing, and managing dependencies.
- Enhanced `.gitignore` to include build artifacts and configuration files.
- Removed unused Prometheus metrics and related code to simplify the codebase.
- Updated dependencies in `go.mod` and `go.sum` for improved functionality and performance.

vfs/vfserror/vfserror.go

@@ -3,16 +3,10 @@ package vfserror
 
 import "errors"
 
+// Common VFS errors
 var (
-	// ErrInvalidKey is returned when a key is invalid.
-	ErrInvalidKey = errors.New("vfs: invalid key")
-
-	// ErrUnreachable is returned when a code path is unreachable.
-	ErrUnreachable = errors.New("unreachable")
-
-	// ErrNotFound is returned when a key is not found.
-	ErrNotFound = errors.New("vfs: key not found")
-
-	// ErrDiskFull is returned when the disk is full.
-	ErrDiskFull = errors.New("vfs: disk full")
+	ErrNotFound         = errors.New("vfs: key not found")
+	ErrInvalidKey       = errors.New("vfs: invalid key")
+	ErrAlreadyExists    = errors.New("vfs: key already exists")
+	ErrCapacityExceeded = errors.New("vfs: capacity exceeded")
 )