platform: modularize api/gui, add docs-tests-web foundation, and refresh root config

selective-vpn-web/src/shared/api/http.ts

@@ -0,0 +1,62 @@
+import { env } from '../config/env'
+
+type RequestJsonOptions = Omit<RequestInit, 'body'> & {
+  timeoutMs?: number
+  body?: unknown
+}
+
+export class HttpError extends Error {
+  public readonly status: number
+  public readonly payload: string
+
+  constructor(message: string, status: number, payload: string) {
+    super(message)
+    this.status = status
+    this.payload = payload
+  }
+}
+
+export function apiUrl(path: string): string {
+  const normalizedPath = path.startsWith('/') ? path : `/${path}`
+  if (!env.apiBaseUrl) {
+    return normalizedPath
+  }
+  return `${env.apiBaseUrl}${normalizedPath}`
+}
+
+export async function requestJson<T>(path: string, options: RequestJsonOptions = {}): Promise<T> {
+  const controller = new AbortController()
+  const timeoutMs = options.timeoutMs ?? 8000
+
+  const headers = new Headers(options.headers || {})
+  const hasBody = options.body !== undefined
+  if (hasBody && !headers.has('Content-Type')) {
+    headers.set('Content-Type', 'application/json')
+  }
+
+  const timeout = setTimeout(() => {
+    controller.abort()
+  }, timeoutMs)
+
+  try {
+    const response = await fetch(apiUrl(path), {
+      ...options,
+      headers,
+      body: hasBody ? JSON.stringify(options.body) : undefined,
+      signal: controller.signal,
+    })
+
+    const text = await response.text()
+    if (!response.ok) {
+      throw new HttpError(`Request failed: ${response.status}`, response.status, text)
+    }
+
+    if (!text) {
+      return {} as T
+    }
+
+    return JSON.parse(text) as T
+  } finally {
+    clearTimeout(timeout)
+  }
+}