feat(users): automatically send the set-password email on user creation

Admin used to have to click 'Send Email' separately after creating a
passwordless user. Now the first set-password email is sent right away
as part of creation — best-effort: if the webhook isn't configured or
the send fails, the user is still created successfully, and the existing
'Send Email' button remains available to retry with proper error
surfacing.

backend/tests/test_password_setup_flow.py

@@ -18,6 +18,41 @@ def new_user_id(api, auth_headers):
     return resp.json()["id"]
 
 
+def test_create_user_automatically_sends_set_password_email(api, db, auth_headers):
+    api(
+        "patch", "/api/v1/system/email-webhook-config", auth_headers,
+        json={"url": "https://example.com/power-automate-hook"},
+    )
+
+    with patch("app.services.webhook_email_service.requests.post") as mock_post:
+        resp = api(
+            "post", "/api/v1/users", auth_headers,
+            json={"full_name": "Auto Send User", "email": "autosend@test.com", "role": "viewer"},
+        )
+    assert resp.status_code == 201, resp.text
+    mock_post.assert_called_once()
+    payload = mock_post.call_args.kwargs["json"]
+    assert payload["to"] == "autosend@test.com"
+    assert payload["subject"] == "Set Your Password"
+    assert "token=" in payload["body"]
+
+    from app.models.password_setup_token import PasswordSetupToken
+    token_row = db.query(PasswordSetupToken).filter(
+        PasswordSetupToken.user_id == uuid.UUID(resp.json()["id"]),
+    ).first()
+    assert token_row is not None
+
+
+def test_create_user_succeeds_even_if_auto_send_fails(api, auth_headers):
+    """No webhook configured yet — the automatic first-email attempt fails,
+    but user creation itself must still succeed."""
+    resp = api(
+        "post", "/api/v1/users", auth_headers,
+        json={"full_name": "No Webhook User", "email": "nowebhook@test.com", "role": "viewer"},
+    )
+    assert resp.status_code == 201, resp.text
+
+
 def test_send_password_email_requires_webhook_configured(api, auth_headers, new_user_id):
     resp = api("post", f"/api/v1/users/{new_user_id}/send-password-email", auth_headers)
     assert resp.status_code == 400