refactor(api): version routes and externalize client base url

- serve REST endpoints under /api/v1 with root exceptions for health and mcp

- move swagger UI to /docs and allow direct frontend calls via CORS

- remove Vite proxy/hash routing and rely on env-driven VITE_API_URL

client/.env.example

@@ -0,0 +1,3 @@
+# Frontend API base URL.
+# Example for local Docker server: backend container is exposed on localhost:13000.
+VITE_API_URL=http://localhost:13000/api/v1

client/src/api/client.ts

@@ -13,9 +13,9 @@ import type {
 } from './types';
 import { emitApiErrorToast } from '../lib/toast-events';
 
-// In dev, Vite proxies /environments /sessions /scenarios to localhost:3000.
-// In production (or when VITE_API_URL is set) we hit the configured origin directly.
-const BASE_URL: string = (import.meta.env.VITE_API_URL as string | undefined) ?? '';
+// API calls are versioned under /api/v1 by default.
+// Set VITE_API_URL (for example, http://localhost:13000/api/v1) to use a different origin.
+const BASE_URL = ((import.meta.env.VITE_API_URL as string | undefined) ?? '/api/v1').replace(/\/$/, '');
 
 async function request<T>(path: string, init?: RequestInit): Promise<T> {
   let res: Response;

client/src/main.tsx

@@ -1,6 +1,6 @@
 import { StrictMode } from 'react';
 import { createRoot } from 'react-dom/client';
-import { HashRouter } from 'react-router-dom';
+import { BrowserRouter } from 'react-router-dom';
 import './i18n';
 import './ui/tokens.css';
 import App from './App';
@@ -9,9 +9,9 @@ import { ToastProvider } from './ui';
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
     <ToastProvider>
-      <HashRouter>
+      <BrowserRouter>
         <App />
-      </HashRouter>
+      </BrowserRouter>
     </ToastProvider>
   </StrictMode>,
 );

client/vite.config.ts

@@ -68,15 +68,6 @@ export default defineConfig({
       },
     },
   },
-  server: {
-    proxy: {
-      '/environments': 'http://localhost:13000',
-      '/credentials': 'http://localhost:13000',
-      '/snippets': 'http://localhost:13000',
-      '/sessions': 'http://localhost:13000',
-      '/scenarios': 'http://localhost:13000',
-    },
-  },
   test: {
     projects: [{
       extends: true,