fix(portal): fix isInitializing race condition causing premature redirect

setIsInitializing(false) was in .finally() which fires BEFORE the
outer .then() chain completes, causing redirect to fire before
setSession was called. Now setIsInitializing(false) is called
explicitly inside success/error handlers after setSession completes.

Co-Authored-By: Paperclip <noreply@paperclip.ing>

apps/web/src/portal/CustomerPortal.tsx

@@ -86,6 +86,7 @@ export function CustomerPortal() {
         .then((r) => {
           if (!r.ok) {
             setSessionError("Failed to create portal session. Please try again.");
+            setIsInitializing(false);
             return null;
           }
           return r.json() as Promise<ImpersonationSession>;
@@ -96,11 +97,12 @@ export function CustomerPortal() {
             setClientName(devUser.name);
             setSessionError(null);
           }
+          setIsInitializing(false);
         })
         .catch(() => {
           setSessionError("Failed to connect. Please check your connection and try again.");
-        })
-        .finally(() => setIsInitializing(false));
+          setIsInitializing(false);
+        });
     } else {
       // No sessionId param and no dev user — init is complete with no session
       setIsInitializing(false);