Update how users and invitations are managed within the system

Corrects the API request method for resending invitations, deleting invitations, and manually creating users in the `InvitationManagement` component.

Replit-Commit-Author: Agent
Replit-Commit-Session-Id: 3a22ac80-cd1d-4441-9e36-f24fc2f4c3de
Replit-Commit-Checkpoint-Type: intermediate_checkpoint
Replit-Commit-Screenshot-Url: https://storage.googleapis.com/screenshot-production-us-central1/3478f7c3-db8c-4fca-9165-3adbdf1b5829/3a22ac80-cd1d-4441-9e36-f24fc2f4c3de/gBqmpbl

.replit

@@ -14,10 +14,6 @@ run = ["npm", "run", "start"]
 localPort = 5000
 externalPort = 80
 
-[[ports]]
-localPort = 35473
-externalPort = 3000
-
 [workflows]
 runButton = "Project"
 

client/src/components/admin/InvitationManagement.tsx

@@ -40,9 +40,7 @@ export function InvitationManagement({ invitations }: InvitationManagementProps)
   // Resend invitation mutation
   const resendInvitationMutation = useMutation({
     mutationFn: async (invitationId: number) => {
-      await apiRequest(`/api/invitations/${invitationId}/resend`, {
-        method: "POST"
-      });
+      await apiRequest("POST", `/api/invitations/${invitationId}/resend`);
     },
     onSuccess: () => {
       toast({
@@ -64,9 +62,7 @@ export function InvitationManagement({ invitations }: InvitationManagementProps)
   // Delete invitation mutation
   const deleteInvitationMutation = useMutation({
     mutationFn: async (invitationId: number) => {
-      await apiRequest(`/api/invitations/${invitationId}`, {
-        method: "DELETE"
-      });
+      await apiRequest("DELETE", `/api/invitations/${invitationId}`);
     },
     onSuccess: () => {
       toast({
@@ -87,11 +83,7 @@ export function InvitationManagement({ invitations }: InvitationManagementProps)
   // Manual user creation mutation
   const createUserMutation = useMutation({
     mutationFn: async (userData: typeof manualUserData) => {
-      await apiRequest("/api/users/create-manual", {
-        method: "POST",
-        body: JSON.stringify(userData),
-        headers: { "Content-Type": "application/json" }
-      });
+      await apiRequest("POST", "/api/users/create-manual", userData);
     },
     onSuccess: () => {
       toast({