feat: show commit hash in index route

only works on coolify or if you specify the SOURCE_COMMIT environment
variable manually

internal/server/router.go

@@ -57,6 +57,7 @@ func NewRouter() {
 			json.NewEncoder(w).Encode(map[string]string{
 				"name":   "trafficlunar's api",
 				"url":    "https://github.com/trafficlunar/api",
+				"commit": os.Getenv("SOURCE_COMMIT")[:7], // shorten to 7 characters
 			})
 		})
 		r.Get("/favicon.ico", func(w http.ResponseWriter, r *http.Request) {