feat: PeopleLib 开放文献客户端，集成 Z-Library 与 LibGen 等多源检索

Electron 桌面客户端，聚合多个开放获取文献源的搜索、详情与下载。

新增数据源：
- Z-Library：邮箱登录（凭据本地存储），会话失效自动重登
- LibGen：适配新版 libgen.ac 前端（旧版 search.php 镜像已全部下线）
- Memory of the World、Sci-Hub、Anna's Archive

基础设施：
- mirror.js：镜像故障转移，支持串行优先与并发竞速两种策略，
  失效镜像 5 分钟冷却后自动重试，避免站点恢复后被永久跳过
- http.js：统一 15 秒请求超时，防止单个卡死镜像拖垮整次搜索
- settings.js：全局代理配置持久化，经 Electron net.fetch 生效于所有请求

Co-authored-by: factory-droid[bot] <138933559+factory-droid[bot]@users.noreply.github.com>

src/sources/http.js

@@ -0,0 +1,148 @@
+const UA = 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0 Safari/537.36';
+
+// 代理配置：默认直连（空字符串）。一旦设置，所有 HTTP 请求统一走该代理。
+// 持久化存储在 userData/settings.json 的 "proxy" 字段。
+let proxyUrl = '';
+let dispatcher = null;
+
+function setProxy(url) {
+  proxyUrl = String(url || '').trim();
+  dispatcher = null;
+  if (!proxyUrl) return;
+  // Electron 下由 session.setProxy 统一接管代理，不需要 undici dispatcher。
+  // 仅在纯 Node 环境（脚本/测试）才构建 ProxyAgent。
+  if (process.versions.electron) return;
+  try {
+    const { ProxyAgent } = require('undici');
+    dispatcher = new ProxyAgent({
+      uri: proxyUrl,
+      requestTls: { rejectUnauthorized: false }
+    });
+  } catch (e) {
+    console.warn('代理初始化失败:', e.message);
+  }
+}
+
+function getProxy() { return proxyUrl; }
+
+function fetchWithProxy(url, options = {}) {
+  // 在 Electron 主进程中优先使用 net.fetch（走 Chromium 网络栈，由 session.setProxy 控制代理）
+  if (process.versions.electron) {
+    try {
+      const { net } = require('electron');
+      return net.fetch(url, options);
+    } catch (e) { /* fallback */ }
+  }
+  if (dispatcher) return fetch(url, { ...options, dispatcher });
+  return fetch(url, options);
+}
+
+// 简易 cookie jar: Map<domain, Map<name, value>>
+const cookieJar = new Map();
+
+function domainOf(url) {
+  try { return new URL(url).hostname; } catch (e) { return ''; }
+}
+
+function getCookies(url) {
+  const d = domainOf(url);
+  const m = cookieJar.get(d);
+  if (!m) return '';
+  return Array.from(m.entries()).map(([k, v]) => `${k}=${v}`).join('; ');
+}
+
+function setCookies(url, setCookieHeaders) {
+  if (!setCookieHeaders || !setCookieHeaders.length) return;
+  const d = domainOf(url);
+  if (!d) return;
+  let m = cookieJar.get(d);
+  if (!m) { m = new Map(); cookieJar.set(d, m); }
+  for (const sc of setCookieHeaders) {
+    const pair = String(sc).split(';')[0];
+    const eq = pair.indexOf('=');
+    if (eq > 0) m.set(pair.slice(0, eq).trim(), pair.slice(eq + 1).trim());
+  }
+}
+
+function clearCookies(urlPrefix) {
+  if (!urlPrefix) { cookieJar.clear(); return; }
+  for (const k of cookieJar.keys()) {
+    if (k.includes(urlPrefix)) cookieJar.delete(k);
+  }
+}
+
+// 默认请求超时（毫秒）。没有超时时，单个卡死的镜像会拖死整次搜索。
+const DEFAULT_TIMEOUT = 15000;
+
+async function fetchRaw(url, options = {}) {
+  const cookie = getCookies(url);
+  const headers = {
+    'User-Agent': UA,
+    'Accept': 'application/json, application/atom+xml, application/xml, text/xml, text/html, */*',
+    ...(options.headers || {})
+  };
+  if (cookie && !headers.Cookie) headers.Cookie = cookie;
+
+  const { timeout, ...rest } = options;
+  const ms = timeout === undefined ? DEFAULT_TIMEOUT : timeout;
+
+  let signal = rest.signal;
+  let timer = null;
+  if (!signal && ms > 0) {
+    const ac = new AbortController();
+    signal = ac.signal;
+    timer = setTimeout(() => ac.abort(), ms);
+  }
+
+  try {
+    const res = await fetchWithProxy(url, { redirect: 'follow', ...rest, headers, signal });
+    const setCookie = res.headers.getSetCookie ? res.headers.getSetCookie() : [];
+    setCookies(url, setCookie);
+    return res;
+  } catch (e) {
+    if (e && (e.name === 'AbortError' || /abort/i.test(e.message || ''))) {
+      throw new Error(`请求超时: ${url}`);
+    }
+    throw e;
+  } finally {
+    if (timer) clearTimeout(timer);
+  }
+}
+
+async function fetchText(url, options = {}) {
+  const res = await fetchRaw(url, options);
+  if (!res.ok) throw new Error(`请求失败: ${res.status} ${url}`);
+  return res.text();
+}
+
+async function fetchJson(url, options = {}) {
+  const text = await fetchText(url, options);
+  try {
+    return JSON.parse(text);
+  } catch (e) {
+    throw new Error(`JSON 解析失败: ${url}`);
+  }
+}
+
+function decodeEntities(s) {
+  if (s == null) return '';
+  return String(s)
+    .replace(/&lt;/g, '<')
+    .replace(/&gt;/g, '>')
+    .replace(/&quot;/g, '"')
+    .replace(/&#39;|&apos;/g, "'")
+    .replace(/&#(\d+);/g, (_, n) => String.fromCodePoint(parseInt(n, 10)))
+    .replace(/&amp;/g, '&');
+}
+
+function stripTags(s) {
+  return decodeEntities(String(s == null ? '' : s).replace(/<[^>]*>/g, ' ')).replace(/\s+/g, ' ').trim();
+}
+
+function clampPage(n, min) {
+  n = parseInt(n, 10);
+  if (!Number.isFinite(n) || n < (min || 1)) return min || 1;
+  return n;
+}
+
+module.exports = { UA, fetchRaw, fetchText, fetchJson, decodeEntities, stripTags, clampPage, getCookies, setCookies, clearCookies, setProxy, getProxy, fetchWithProxy };