Owner settings: add a real delete for Mitarbeiter (barbers)

Rename + active-toggle already existed (this session, earlier commit)
-- this adds a genuine, permanent delete alongside them, guarded by a
confirm() prompt that points to the "Aktiv" checkbox as the reversible
alternative for someone just temporarily off. Existing bookings against
a deleted resource are left as-is (no FK in this schema, matching its
existing convention) -- the owner agenda already falls back to the raw
resource_id for a booking whose resource no longer resolves, same as
it does today for a deactivated one.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

backoffice/app/tests/test_owner_settings.py

@@ -166,6 +166,23 @@ def test_owner_cannot_update_another_tenants_resource(client):
     assert bdb.get_resource(CLIENT_B, resource_b["resource_id"])["max_advance_days"] != 1
 
 
+def test_owner_can_delete_a_resource(client):
+    resource, service = _setup(CLIENT_A)
+    _login(client, CLIENT_A)
+    resp = client.post(f"/owner/settings/resources/{resource['resource_id']}/delete")
+    assert "error" not in resp.headers["Location"]
+    assert bdb.get_resource(CLIENT_A, resource["resource_id"]) is None
+
+
+def test_owner_cannot_delete_another_tenants_resource(client):
+    resource_b, service_b = _setup(CLIENT_B)
+    _setup(CLIENT_A)
+    _login(client, CLIENT_A)
+    resp = client.post(f"/owner/settings/resources/{resource_b['resource_id']}/delete")
+    assert "error=not_found" in resp.headers["Location"]
+    assert bdb.get_resource(CLIENT_B, resource_b["resource_id"]) is not None
+
+
 # ---- locations / resources self-service ----
 
 def test_owner_can_create_location(client):