test: trim purge-identity tests to behaviour invariants

Drop the three cases that pin trivia the invariant tests already cover
(idempotence is exercised by the routing-store test; the empty-name /
no-store guard and the default-profile refusal are one-line argument
checks). Salvage bar: invariants only.

tests/gateway/test_profile_identity_purge.py

@@ -121,11 +121,3 @@ def test_purge_verb_drops_routing_identity_and_reports_ok(tmp_path):
             "SELECT COUNT(*) AS n FROM gateway_heartbeats WHERE profile = ?", ("gone",))["n"] == 0
     finally:
         db.close()
-
-
-def test_purge_verb_refuses_without_a_name_or_store():
-    """A malformed request or a gateway with no store answers failure — never a silent success."""
-    from gateway.run_profile_reconcile import purge_profile_identity_verb
-    no_store = purge_profile_identity_verb(SimpleNamespace(session_store=None))
-    assert no_store({})["ok"] is False
-    assert no_store({"name": "gone"})["ok"] is False

tests/hermes_cli/test_profile_identity_purge_cmd.py

@@ -53,12 +53,6 @@ def test_purge_identity_exits_nonzero_when_settlement_stays_pending(
     assert "hermes profile purge-identity gone" in capsys.readouterr().err
 
 
-def test_purge_identity_rejects_the_default_profile(profile_env, capsys):
-    with pytest.raises(SystemExit):
-        profile_cmd.cmd_profile(Namespace(profile_action="purge-identity", profile_name="default"))
-    assert "named profiles only" in capsys.readouterr().out
-
-
 def test_purge_identity_refuses_a_same_name_profile_created_after_the_delete(profile_env, capsys):
     """The retry must not purge identity out from under a profile that exists again.
 

tests/hermes_state/test_purge_profile_state.py

@@ -150,10 +150,3 @@ class TestPurgeProfileState:
         routing = db.load_gateway_routing_entries(scope="/root/sessions")
         assert "agent:foo_bar:feishu:dm:chatA" not in routing
         assert "agent:fooXbar:feishu:dm:chatB" in routing
-
-    def test_purge_is_idempotent(self, db):
-        db.register_backend_heartbeat(
-            backend_id="be1", pid=1, started_at=time.time(), profile="gone", host="h")
-
-        assert db.purge_profile_state("gone")["gateway_heartbeats"] == 1
-        assert db.purge_profile_state("gone")["gateway_heartbeats"] == 0