feat: cache + paths (#1)

- Added helper function `ExpandUser`
- Added basic cache impmentations for in-memory and file based caches.

Reviewed-on: #1
Co-authored-by: Felipe M. <me@fmartingr.com>
Co-committed-by: Felipe M. <me@fmartingr.com>

model/cache.go

@@ -0,0 +1,22 @@
+package model
+
+import (
+	"errors"
+	"time"
+)
+
+var ErrCacheKeyDontExist = errors.New("cache key don't exist")
+
+type Cache interface {
+	Get(key string) (any, error)
+	Set(key string, value any, opts ...CacheOption) error
+	Delete(key string) error
+}
+
+type CacheItem struct {
+	Key   string
+	Value any
+	TTL   *time.Time
+}
+
+type CacheOption func(item *CacheItem)