feat: reset proxy cache with sigusr2

internal/cache/ttl/cache.go

@@ -28,6 +28,11 @@ func (c *Cache[K, V]) Set(key K, value V) {
 	c.values.Set(key, value)
 }
 
+func (c *Cache[K, V]) Clear() {
+	c.timestamps.Clear()
+	c.values.Clear()
+}
+
 func NewCache[K comparable, V any](values cache.Cache[K, V], timestamps cache.Cache[K, time.Time], ttl time.Duration) *Cache[K, V] {
 	return &Cache[K, V]{
 		values:     values,