v0.1.2 — accurate no-args hint

What changed

The no-args warning in action.yml said args: check path/to/your/file on every
gate. check is only context-gate's subcommand — the correct usage for this gate is:

- uses: chenhz01/context-gate@v0.1.2
  with:
    args: "bench --input path/to/units.json --budget 600"

Nothing else changed: gate.py is byte-identical to v0.1.1.

Why it matters

If you mount the action without args, it prints help and exits 0 — a green
check that inspected nothing. The warning annotation now quotes this gate's real
usage, so the fix is one copy-paste away instead of a wrong hint.

Pin the newest tag

The README used to pin @v0.1.0. That version predates the fix that makes a
mistyped path exit 2 instead of silently scanning zero files and passing.
Use @v0.1.2.

Exit codes for this gate

The bundled example exits 0 (the benchmark ran; exceeding --budget is reported, not enforced).