Add emotes HTML page at /, health endpoint, Dockerfile, and Docker workflow

src/main.rs

@@ -54,6 +54,7 @@ async fn main() {
 
     let app = Router::new()
         .route("/", get(routes::emotes::root))
+        .route("/health", get(routes::health::health))
         .route("/version", get(routes::version::version))
         .route("/json", get(routes::emotes::list_emotes))
         .route("/emotes", post(routes::emotes::create_emote))