Add justfile and essential recipes. Add unit tests. Add linter and fix linter errors.

ui/src/api/index.ts

@@ -1,12 +1,8 @@
 import { action, query } from "@solidjs/router";
-
-const API_BASE_URL = process.env.API_BASE_URL ?? "http://localhost:5013";
-
-const buildUrl = (path: string) =>
-  `${API_BASE_URL.replace(/\/+$/, "")}/${path.replace(/^\/+/, "")}`;
+import { buildApiUrl } from "./url";
 
 async function fetchApi<T>(path: string, init?: RequestInit): Promise<T> {
-  const response = await fetch(buildUrl(path), {
+  const response = await fetch(buildApiUrl(path), {
     ...init,
     headers: {
       "content-type": "application/json",