Move invite flow to client navigation

backend/app/routers/auth.py

@@ -102,6 +102,12 @@ def _require_recipient_email(value: object) -> str:
     )
 
 
+def _optional_recipient_email(value: object) -> str | None:
+    if value is None or not str(value).strip():
+        return None
+    return _require_recipient_email(value)
+
+
 def _auth_client_ip(request: Request) -> str:
     direct_host = request.client.host if request.client else None
     if request_trusts_forwarded_headers(direct_host):
@@ -1210,8 +1216,10 @@ async def create_profile_invite(payload: dict, current_user: dict = Depends(get_
         label = str(label).strip() or None
     if description is not None:
         description = str(description).strip() or None
-    recipient_email = _require_recipient_email(recipient_email)
     send_email = bool(payload.get("send_email"))
+    recipient_email = _optional_recipient_email(recipient_email)
+    if send_email and not recipient_email:
+        recipient_email = _require_recipient_email(recipient_email)
     delivery_message = str(payload.get("message") or "").strip() or None
 
     master_invite = _get_self_service_master_invite()
@@ -1300,8 +1308,10 @@ async def update_profile_invite(
         label = str(label).strip() or None
     if description is not None:
         description = str(description).strip() or None
-    recipient_email = _require_recipient_email(recipient_email)
     send_email = bool(payload.get("send_email"))
+    recipient_email = _optional_recipient_email(recipient_email)
+    if send_email and not recipient_email:
+        recipient_email = _require_recipient_email(recipient_email)
     delivery_message = str(payload.get("message") or "").strip() or None
 
     master_invite = _get_self_service_master_invite()