feat(a0): 完成工程骨架与契约基线

- 建立 pnpm workspace + Turborepo 单仓、ESLint 9/Prettier/commitlint/husky 门禁
- NestJS + Fastify API：统一错误体、trace_id、Zod 管道、/health 真实依赖探活、OpenAPI 3.1 契约
- Prisma 基线：outbox_events/idempotency_keys/system_configs 与首版迁移、幂等种子
- shared 契约包：错误码、权限点、ULID、游标分页、命名/时间工具
- ui 包与 Web 壳层：Semi + Remix 图标统一出口、Cloud Blue 视觉、登录/工作台/错误页
- worker 骨架、Playwright 冒烟、Gitea CI、OpenAPI 快照与 oasdiff 回退脚本
- 补充 A0 实施报告与本地开发说明

apps/web/src/layout/SideNav.tsx

@@ -0,0 +1,59 @@
+import { IconBack, IconMenu } from '@lingxi/ui/icons';
+import type { ReactNode } from 'react';
+import { NavLink } from 'react-router';
+
+import type { NavModule } from '@/navigation/nav-config';
+
+export interface SideNavProps {
+  module: NavModule;
+  collapsed: boolean;
+  onToggle: () => void;
+}
+
+export function SideNav({ module, collapsed, onToggle }: SideNavProps): ReactNode {
+  return (
+    <aside className="lx-sidebar" aria-label="功能导航">
+      <div className="lx-sidebar__heading">
+        <span className="lx-sidebar__title">{module.label}</span>
+        <button
+          type="button"
+          className="lx-icon-button lx-sidebar__toggle"
+          onClick={onToggle}
+          aria-label={collapsed ? '展开侧边栏' : '收起侧边栏'}
+          title={collapsed ? '展开侧边栏' : '收起侧边栏'}
+        >
+          {collapsed ? <IconMenu size={18} /> : <IconBack size={18} />}
+        </button>
+      </div>
+
+      <nav className="lx-sidebar__nav">
+        {module.items.map((item) => {
+          const Icon = item.icon;
+          return (
+            <NavLink
+              key={item.key}
+              to={item.path}
+              end={item.path === '/'}
+              className={({ isActive }) =>
+                isActive ? 'lx-sidebar__item is-active' : 'lx-sidebar__item'
+              }
+              title={collapsed ? item.label : undefined}
+            >
+              <span className="lx-sidebar__item-icon">
+                <Icon size={18} />
+              </span>
+              <span className="lx-sidebar__item-label">{item.label}</span>
+            </NavLink>
+          );
+        })}
+      </nav>
+
+      <div className="lx-sidebar__footer">
+        <span className="lx-sidebar__env" title="当前环境：本地开发">
+          <span className="lx-sidebar__env-dot" aria-hidden="true" />
+          <span className="lx-sidebar__env-text">本地开发</span>
+        </span>
+      </div>
+    </aside>
+  );
+}