FIX: pyrit_shell run fails for every scenario with a flag-collision error

[jsong468]

Bug Description

Running any scenario from pyrit_shell failed before argument parsing with:

Error: Scenario parameter flag '--memory-labels' collides with a built-in flag. Rename the parameter to avoid the collision.

Root cause: The shell registers each of a scenario's parameters as a CLI flag, using the full list from the API (scenario_meta.supported_parameters). That list combines the scenario's custom parameters with the framework's common parameters (memory_labels, max_concurrency, max_retries), which normalize to flags that already exist as built-in shell flags. The collision guard _validate_scenario_flag_collisions raised on the first such clash (memory_labels) instead of skipping it. Since every scenario carries the common parameters, run was broken universally.

pyrit_scan was unaffected: its _add_scenario_params_from_api silently skips any scenario flag that already exists as a built-in. The inconsistency between the two entry points was the bug.

Fix

Make the shell mirror pyrit_scan. Replaced _validate_scenario_flag_collisions with _resolve_scenario_flag_collisions in pyrit/cli/_cli_args.py, which silently drops any scenario spec whose flag is already taken — by a built-in flag or an earlier scenario param — so the earlier owner keeps the flag (first wins). This matches pyrit_scan._add_scenario_params_from_api, which skips any flag already registered on the parser, so both entry points now accept the same inputs.

parse_run_arguments now uses the returned filtered specs rather than relying on a validator side effect.

Testing

• Added tests/unit/cli/test_cli_args.py::test_parse_run_arguments_skips_scenario_params_colliding_with_builtins — reproduces the airt.scam case (common params present) and asserts run parses successfully while the scenario's custom --max-turns flag still works.
• Added tests/unit/cli/test_cli_args.py::test_parse_run_arguments_first_wins_on_scenario_vs_scenario_collision — confirms two scenario params normalizing to the same flag resolve first-wins (parity with pyrit_scan), not an error.
• New tests pass. Full test_cli_args.py + test_pyrit_shell.py suites pass (86/86), no regressions.