fix: cover remaining config placeholder help text

Update the unknown-subcommand config help output to use placeholder syntax too,
and extend the placeholder regression tests to cover show_config() and that
fallback help path.

hermes_cli/config.py

@@ -1506,7 +1506,7 @@ def config_command(args):
         print("Available commands:")
         print("  hermes config           Show current configuration")
         print("  hermes config edit      Open config in editor")
-        print("  hermes config set K V   Set a config value")
+        print("  hermes config set <key> <value>   Set a config value")
         print("  hermes config check     Check for missing/outdated config")
         print("  hermes config migrate   Update config with new options")
         print("  hermes config path      Show config file path")

tests/hermes_cli/test_placeholder_usage.py

@@ -6,7 +6,7 @@ from unittest.mock import patch
 
 import pytest
 
-from hermes_cli.config import config_command
+from hermes_cli.config import config_command, show_config
 from hermes_cli.setup import _print_setup_summary
 
 
@@ -21,6 +21,25 @@ def test_config_set_usage_marks_placeholders(capsys):
     assert "Usage: hermes config set <key> <value>" in out
 
 
+def test_config_unknown_command_help_marks_placeholders(capsys):
+    args = Namespace(config_command="wat")
+
+    with pytest.raises(SystemExit) as exc:
+        config_command(args)
+
+    assert exc.value.code == 1
+    out = capsys.readouterr().out
+    assert "hermes config set <key> <value>   Set a config value" in out
+
+
+def test_show_config_marks_placeholders(tmp_path, capsys):
+    with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
+        show_config()
+
+    out = capsys.readouterr().out
+    assert "hermes config set <key> <value>" in out
+
+
 def test_setup_summary_marks_placeholders(tmp_path, capsys):
     with patch.dict(os.environ, {"HERMES_HOME": str(tmp_path)}):
         _print_setup_summary({"tts": {"provider": "edge"}}, tmp_path)