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/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>,
 );