good progress yay:

- impl http client
- create http client in App()
- generic builder for Service.*
- set Service on app to pass to callbacks later
- impl State
- set State on app to pass to callbacks later
- change panic to log.Fatalln

state.go

@@ -0,0 +1,20 @@
+package gomeassistant
+
+import "github.com/saml-dev/gome-assistant/internal/http"
+
+// State is used to retrieve state from Home Assistant.
+type State struct {
+	httpClient *http.HttpClient
+}
+
+func NewState(c *http.HttpClient) *State {
+	return &State{httpClient: c}
+}
+
+func (s *State) Get(entityId string) (string, error) {
+	resp, err := s.httpClient.GetState(entityId)
+	if err != nil {
+		return "", err
+	}
+	return string(resp), nil
+}