refactor(tests): re-architect tests + fix CI failures (#5946)

* refactor: re-architect tests to mirror the codebase

* Update tests.yml

* fix: add missing tool_error imports after registry refactor

* fix(tests): replace patch.dict with monkeypatch to prevent env var leaks under xdist

patch.dict(os.environ) can leak TERMINAL_ENV across xdist workers,
causing test_code_execution tests to hit the Modal remote path.

* fix(tests): fix update_check and telegram xdist failures

- test_update_check: replace patch("hermes_cli.banner.os.getenv") with
  monkeypatch.setenv("HERMES_HOME") — banner.py no longer imports os
  directly, it uses get_hermes_home() from hermes_constants.

- test_telegram_conflict/approval_buttons: provide real exception classes
  for telegram.error mock (NetworkError, TimedOut, BadRequest) so the
  except clause in connect() doesn't fail with "catching classes that do
  not inherit from BaseException" when xdist pollutes sys.modules.

* fix(tests): accept unavailable_models kwarg in _prompt_model_selection mock

tests/cli/test_cli_skin_integration.py

@@ -0,0 +1,98 @@
+from types import SimpleNamespace
+from unittest.mock import MagicMock, patch
+
+from cli import HermesCLI, _rich_text_from_ansi
+from hermes_cli.skin_engine import get_active_skin, set_active_skin
+
+
+def _make_cli_stub():
+    cli = HermesCLI.__new__(HermesCLI)
+    cli._sudo_state = None
+    cli._secret_state = None
+    cli._approval_state = None
+    cli._clarify_state = None
+    cli._clarify_freetext = False
+    cli._command_running = False
+    cli._agent_running = False
+    cli._voice_recording = False
+    cli._voice_processing = False
+    cli._voice_mode = False
+    cli._command_spinner_frame = lambda: "⟳"
+    cli._tui_style_base = {
+        "prompt": "#fff",
+        "input-area": "#fff",
+        "input-rule": "#aaa",
+        "prompt-working": "#888 italic",
+    }
+    cli._app = SimpleNamespace(style=None)
+    cli._invalidate = MagicMock()
+    return cli
+
+
+class TestCliSkinPromptIntegration:
+    def test_default_prompt_fragments_use_default_symbol(self):
+        cli = _make_cli_stub()
+
+        set_active_skin("default")
+        assert cli._get_tui_prompt_fragments() == [("class:prompt", "❯ ")]
+
+    def test_ares_prompt_fragments_use_skin_symbol(self):
+        cli = _make_cli_stub()
+
+        set_active_skin("ares")
+        assert cli._get_tui_prompt_fragments() == [("class:prompt", "⚔ ❯ ")]
+
+    def test_secret_prompt_fragments_preserve_secret_state(self):
+        cli = _make_cli_stub()
+        cli._secret_state = {"response_queue": object()}
+
+        set_active_skin("ares")
+        assert cli._get_tui_prompt_fragments() == [("class:sudo-prompt", "🔑 ❯ ")]
+
+    def test_icon_only_skin_symbol_still_visible_in_special_states(self):
+        cli = _make_cli_stub()
+        cli._secret_state = {"response_queue": object()}
+
+        with patch("hermes_cli.skin_engine.get_active_prompt_symbol", return_value="⚔ "):
+            assert cli._get_tui_prompt_fragments() == [("class:sudo-prompt", "🔑 ⚔ ")]
+
+    def test_build_tui_style_dict_uses_skin_overrides(self):
+        cli = _make_cli_stub()
+
+        set_active_skin("ares")
+        skin = get_active_skin()
+        style_dict = cli._build_tui_style_dict()
+
+        assert style_dict["prompt"] == skin.get_color("prompt")
+        assert style_dict["input-rule"] == skin.get_color("input_rule")
+        assert style_dict["prompt-working"] == f"{skin.get_color('banner_dim')} italic"
+        assert style_dict["approval-title"] == f"{skin.get_color('ui_warn')} bold"
+
+    def test_apply_tui_skin_style_updates_running_app(self):
+        cli = _make_cli_stub()
+
+        set_active_skin("ares")
+        assert cli._apply_tui_skin_style() is True
+        assert cli._app.style is not None
+        cli._invalidate.assert_called_once_with(min_interval=0.0)
+
+    def test_handle_skin_command_refreshes_live_tui(self, capsys):
+        cli = _make_cli_stub()
+
+        with patch("cli.save_config_value", return_value=True):
+            cli._handle_skin_command("/skin ares")
+
+        output = capsys.readouterr().out
+        assert "Skin set to: ares (saved)" in output
+        assert "Prompt + TUI colors updated." in output
+        assert cli._app.style is not None
+
+
+class TestAnsiRichTextHelper:
+    def test_preserves_literal_brackets(self):
+        text = _rich_text_from_ansi("[notatag] literal")
+        assert text.plain == "[notatag] literal"
+
+    def test_strips_ansi_but_keeps_plain_text(self):
+        text = _rich_text_from_ansi("\x1b[31mred\x1b[0m")
+        assert text.plain == "red"