Fix Windows system-path detection and make CLI help assertions robust

[AperturePlus]

Motivation

• Prevent false negatives when detecting Windows system directories on non-Windows hosts by handling drive/root prefixes consistently for paths like C:\Program Files (x86).
• Make CLI help tests resilient to Rich/Typer output differences (ANSI sequences and layout) to avoid brittle assertions in CI.

Description

• Adjust _is_windows_system_directory in src/aci/core/path_utils.py to normalize the first Windows path part using rstrip("\\/") before matching drive letters so drive roots are stripped reliably.
• Harden tests/unit/test_cli.py by removing ANSI escape sequences from command output and asserting on stable tokens (workers, limit, filter, -w) instead of exact long-option rendering.

Testing

• Ran a quick reproduction invoking _is_windows_system_directory with Path(r"C:\\Program Files (x86)") which returned True as expected.
• Executed pytest tests/unit/test_cli.py::TestCLIHelp::test_index_help tests/unit/test_cli.py::TestCLIHelp::test_search_help -q and both tests passed.
• Attempted to run the property tests that originally failed but collection failed in this environment due to missing hypothesis (error: ModuleNotFoundError: No module named 'hypothesis'), so full property-suite verification could not be completed here.

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Codex Task