Honor -- when filtering base-bash wrapper arguments

[codeforester]

Problem

The stdlib initializer and standalone launcher scan every argument for wrapper flags. They do not stop at the conventional -- delimiter.

At main commit a107134, sourcing the stdlib with alpha -- --color omega leaves alpha -- omega; the target script can never receive a literal --color after the delimiter. base_bash_filter_runtime_args duplicates the same behavior. It also publishes its temporary result through an undeclared global base_bash_runtime_args.

Separately, base-bash --help prints normal help but exits with status 2, the same as missing required input.

Scope

• Stop wrapper-option interpretation after the first standalone -- and preserve the entire remaining argument tail.
• Keep recognized wrapper flags before the delimiter working as today.
• Ensure top-level target-script arguments and main arguments are identical.
• Keep launcher filtering state local or caller-owned instead of leaking a generic global.
• Return 0 for explicit help and a usage status for a missing script.

Acceptance Criteria

• base-bash script -- --color delivers -- --color to both the sourced script body and main.
• Wrapper flags before -- are consumed exactly once and still configure logging.
• The launcher exposes no filtering scratch global to the target script.
• base-bash --help returns 0; invoking without a script remains a usage failure.

Validation

• bats tests/launcher.bats lib/bash/std/tests/lib_std.bats
• ./tests/validate.sh
• git diff --check

[codeforester]

Implemented by merged PR #172. Stdlib and base-bash wrapper filtering now honors --, keeps scratch state local, and explicit launcher help returns 0. Coverage is in lib/bash/std/tests/lib_std.bats and tests/launcher.bats.