fix: avoid Rich markup parsing for CLI errors

[ekkoitac]

Fixes #422

Summary

• print Rich Text error messages as renderables instead of converting them through f-strings
• print generated tracebacks with markup=False, so bracket-like exception text is shown literally
• add a CLI regression test for an exception message containing [/'A', 1, /'B']

Validation

• uv run --all-extras pytest tests/test_cli.py::TestCli::test_run_prints_markup_like_errors_without_rich_crash -q
• uv run --all-extras pytest tests/test_cli.py -q
• uv run --all-extras ruff check trae_agent/cli.py tests/test_cli.py
• uv run --all-extras python -m py_compile trae_agent/cli.py tests/test_cli.py
• make test (63 passed, 17 skipped; skipped tests require external Google, Ollama, or OpenRouter services)

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