fix: expire invalid CMS sessions cleanly

cms/admin/src/App.tsx

@@ -22,6 +22,11 @@ const SIDEBAR = [
 
 function useAuth(){
   const [token,setToken]=useState(localStorage.getItem('cms_token')||'')
+  useEffect(()=>{
+    const onUnauthorized=()=>setToken('')
+    window.addEventListener('cms:unauthorized',onUnauthorized)
+    return ()=>window.removeEventListener('cms:unauthorized',onUnauthorized)
+  },[])
   const login=async(u:string,p:string)=>{
     const r=await fetch('/api/auth/login',{method:'POST',headers:{'Content-Type':'application/json'},body:JSON.stringify({username:u,password:p})})
     const j=await r.json()
@@ -33,11 +38,17 @@ function useAuth(){
   return {token,login,logout}
 }
 
-function api(path:string, token:string, opts:RequestInit={}){
+async function api(path:string, token:string, opts:RequestInit={}){
   const headers:any={...(opts.headers||{})}
   if(token) headers['Authorization']='Bearer '+token
   if(!(opts.body instanceof FormData)) headers['Content-Type']='application/json'
-  return fetch(path,{...opts, headers}).then(r=>r.json())
+  const response=await fetch(path,{...opts, headers})
+  const result=await response.json()
+  if(response.status===401 || result.code===401){
+    localStorage.removeItem('cms_token')
+    window.dispatchEvent(new Event('cms:unauthorized'))
+  }
+  return result
 }
 
 const FIELD_LABELS:Record<string,string> = {