feat(frontend): file:// bundle support (HashRouter + build:desktop)

- main.tsx: use HashRouter when loaded over file:// (packaged desktop
  has no server for History API path routing); keep BrowserRouter on
  the http web build.
- add build:desktop script (vite build --base=./ --outDir dist-desktop)
  so assets resolve under file://; gitignore dist-desktop.

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

.gitignore

@@ -22,3 +22,4 @@ dist-ssr
 *.njsproj
 *.sln
 *.sw?
+dist-desktop

package.json

@@ -7,7 +7,8 @@
     "dev": "vite",
     "build": "tsc -b && vite build",
     "lint": "eslint .",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "build:desktop": "tsc -b && vite build --base=./ --outDir dist-desktop"
   },
   "dependencies": {
     "axios": "^1.16.0",

src/main.tsx

@@ -1,16 +1,21 @@
 import { StrictMode } from 'react'
 import { createRoot } from 'react-dom/client'
-import { BrowserRouter } from 'react-router-dom'
+import { BrowserRouter, HashRouter } from 'react-router-dom'
 import './index.css'
 import App from './App.tsx'
 import { AuthProvider } from './auth/AuthContext'
 
+// The packaged desktop app loads the bundled SPA over file://, where the
+// History API has no server to back path routing — use HashRouter there.
+// The web build (served over http behind nginx) keeps clean BrowserRouter URLs.
+const Router = window.location.protocol === 'file:' ? HashRouter : BrowserRouter
+
 createRoot(document.getElementById('root')!).render(
   <StrictMode>
-    <BrowserRouter>
+    <Router>
       <AuthProvider>
         <App />
       </AuthProvider>
-    </BrowserRouter>
+    </Router>
   </StrictMode>,
 )