fix: set dummy auth env vars in comment guard test

test_comment_add_human_mode_warns_without_yes relied on TRELLO_API_KEY
and TRELLO_TOKEN being present in the environment. CI runners don't
have them, so TrelloAuth.from_env raised ValueError before the mock
client was reached — exit code 1 instead of 0.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: OG-Drizzles

tests/test_cli.py

@@ -515,6 +515,8 @@ def test_comment_add_human_mode_warns_without_yes(
 
         _setup_cli_cache(tmp_path, monkeypatch)
         # Human mode is already set by _setup_cli_cache
+        monkeypatch.setenv("TRELLO_API_KEY", "dummy")
+        monkeypatch.setenv("TRELLO_TOKEN", "dummy")
 
         mock_comment = MagicMock()
         mock_comment.id = "comment_abc"