feat: create model for pomodoro settings

- introduce GoTomatoTimerConfig
- create instance variable with current config
- update code to use the new variable

pkg/models/config.go

@@ -1,5 +1,12 @@
 package models
 
+type GoTomatoTimerConfig struct {
+	Work       int `json:"work"`
+	ShortBreak int `json:"shortBreak"`
+	LongBreak  int `json:"longBreak"`
+	Sessions   int `json:"sessions"`
+}
+
 type GoTomatoServerConfig struct {
 	ListenAddress string `json:"listenAddress"`
 	ListenPort    int    `json:"listenPort"`