test(tui): pin approval-mode fixtures to env HERMES_HOME for canonical resolver

_load_approval_mode now delegates to tools.approval._get_approval_mode,
which reads config via hermes_cli.config.load_config — that path resolves
HERMES_HOME from the environment, not the server module's _hermes_home
attribute. The four approval-mode tests only monkeypatched the module
attribute, so the resolver silently read the developer/CI real config
(default 'smart') instead of the temp fixture. Behavior assertions are
unchanged (invalid → manual fail-safe, YAML off-bool → 'off', three-way
persist + live emit); the fixtures now also set HERMES_HOME so the
canonical read path sees the same temp config.

tests/test_tui_gateway_server.py

@@ -5313,6 +5313,10 @@ def test_config_get_approval_mode_uses_smart_default_when_key_is_missing(
     import yaml
 
     monkeypatch.setattr(server, "_hermes_home", tmp_path)
+    # Point the canonical resolver (load_config → env HERMES_HOME) at the
+    # temp home too, so the smart default is asserted against THIS config
+    # rather than whatever the developer's real ~/.hermes happens to hold.
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
     (tmp_path / "config.yaml").write_text(
         yaml.safe_dump({"approvals": {"timeout": 15}})
     )
@@ -5329,6 +5333,11 @@ def test_config_get_approval_mode_fails_safe_to_manual_for_invalid_explicit_valu
     import yaml
 
     monkeypatch.setattr(server, "_hermes_home", tmp_path)
+    # _load_approval_mode delegates to the canonical resolver in
+    # tools.approval, which reads via hermes_cli.config.load_config —
+    # that path resolves HERMES_HOME from the environment, not
+    # server._hermes_home.
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
     (tmp_path / "config.yaml").write_text(
         yaml.safe_dump({"approvals": {"mode": "sometimes"}})
     )
@@ -5343,6 +5352,9 @@ def test_config_get_approval_mode_normalizes_yaml_off(tmp_path, monkeypatch):
     import yaml
 
     monkeypatch.setattr(server, "_hermes_home", tmp_path)
+    # See fail-safe test above: the canonical resolver reads via
+    # load_config, which resolves HERMES_HOME from the environment.
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
     (tmp_path / "config.yaml").write_text(
         yaml.safe_dump({"approvals": {"mode": False}})
     )
@@ -5359,6 +5371,10 @@ def test_config_set_approval_mode_persists_three_way_value_and_emits_live_status
     import yaml
 
     monkeypatch.setattr(server, "_hermes_home", tmp_path)
+    # config.set writes via server._hermes_home, but the post-write
+    # session.info emit resolves the effective mode through the canonical
+    # tools.approval resolver (load_config → env HERMES_HOME).
+    monkeypatch.setenv("HERMES_HOME", str(tmp_path))
     emitted = []
     monkeypatch.setattr(server, "_emit", lambda *args: emitted.append(args))
     server._sessions["sid"] = {"agent": object(), "session_key": "profile-session"}