feat(docs): public DocsView with Codex/Claude Code/curl quickstart

Route /docs (no auth). Six sections: get key, codex CLI, claude code,
curl, supported models, feedback. Uses puro.css design system.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

frontend/src/router/index.ts

@@ -120,6 +120,15 @@ const routes: RouteRecordRaw[] = [
       title: 'Key Usage',
     }
   },
+  {
+    path: '/docs',
+    name: 'Docs',
+    component: () => import('@/views/docs/DocsView.vue'),
+    meta: {
+      requiresAuth: false,
+      title: 'PURO AI · 文档'
+    }
+  },
 
   // ==================== User Routes ====================
   {