refactor: 标准化项目结构 frontend/ + backend/ + SQLite + run.sh

- 目录重构: app/ -> frontend/，与 backend/ 并列
- 数据库: 默认 SQLite（零配置），修复 DSN() bug
- run.sh: 一键启动前后端，支持 start/stop/restart/status
- Makefile: install/dev/build/lint/clean 快捷命令
- vite.config.ts: 配置 dev server 端口 5173 + API 代理到 8080
- config.yaml: SQLite 默认配置，开箱即用
- docs/: 完整开发文档（项目结构/API/数据库/规范/部署）
- 修复: GORM foreign key 关联声明
- 修复: go get gorm.io/driver/sqlite 依赖

frontend/vite.config.ts

@@ -0,0 +1,33 @@
+import path from "path"
+import react from "@vitejs/plugin-react"
+import { defineConfig } from "vite"
+import { inspectAttr } from 'kimi-plugin-inspect-react'
+
+// https://vite.dev/config/
+export default defineConfig({
+  base: './',
+  plugins: [inspectAttr(), react()],
+  resolve: {
+    alias: {
+      "@": path.resolve(__dirname, "./src"),
+    },
+  },
+  server: {
+    port: 5173,
+    host: true,
+    proxy: {
+      "/api": {
+        target: "http://localhost:8080",
+        changeOrigin: true,
+      },
+      "/health": {
+        target: "http://localhost:8080",
+        changeOrigin: true,
+      },
+      "/version": {
+        target: "http://localhost:8080",
+        changeOrigin: true,
+      },
+    },
+  },
+})