feat: invite management API: DELETE /v1/user/invite/:id (204, cancels a pending invite) and POST /v1/user/invite/:id/renew (200, new code, expires_at = now+3d, created_at = now, resends the invitation email, old link dead)

api/pkg/apperr/messages.go

@@ -19,6 +19,8 @@ const TooManyRequestsErrorMessage = "Too many requests. Please try again later."
 const EmailHasAccountErrorMessage = "This address already has an account."
 const PendingInviteErrorMessage = "There's already a pending invite for this address."
 const InviteNotSentErrorMessage = "Couldn't send the invite. Try again in a moment."
+const InviteNotFoundErrorMessage = "Invite not found"
+const InviteAlreadyAcceptedErrorMessage = "This invite has already been accepted."
 const InviteInvalidErrorMessage = "This invite link doesn't work."
 const InviteExpiredErrorMessage = "This invite has expired."
 const OwnerRequiredErrorMessage = "Only the owner can do this."