docs: 更新项目说明文档、添加界面截图与镜像加速配置

- 更新 README.md，完善功能特性、技术栈与使用说明
- 添加界面截图到 docs/snipastes 目录
- 配置 Tauri 更新镜像与 GitHub Actions 脚本
- 修正应用名称大小写与更新端点配置

src-tauri/tauri.conf.json

@@ -1,8 +1,8 @@
 {
   "$schema": "https://schema.tauri.app/config/2",
-  "productName": "frpilot",
+  "productName": "Frpilot",
   "version": "../package.json",
-  "identifier": "frpilot",
+  "identifier": "Frpilot",
   "build": {
     "beforeDevCommand": "pnpm dev",
     "devUrl": "http://localhost:1420",
@@ -41,7 +41,10 @@
     "updater": {
       "active": true,
       "dialog": false,
-      "endpoints": ["https://ghproxy.net/https://github.com/SparksFly91/Frpilot/releases/latest/download/latest.json"],
+      "endpoints": [
+        "https://ghproxy.net/https://github.com/SparksFly91/Frpilot/releases/latest/download/latest.json",
+        "https://github.com/SparksFly91/Frpilot/releases/latest/download/latest.json"
+      ],
       "pubkey": "dW50cnVzdGVkIGNvbW1lbnQ6IG1pbmlzaWduIHB1YmxpYyBrZXk6IEU0REVGMTREODFFOTI2MUEKUldRYUp1bUJUZkhlNU1qRmlPQm5xSmdQd24waFltVmNtTjlUallYVmdva1VGNkp5bTVGcVlsZUgK"
     }
   }