util: take circuit path as CLI arg instead of hardcoding

[midasbal]

Description

Both binaries in util/ hardcoded the input circuit path
(/Users/user/g16.ckt), so choosing a different circuit file meant editing the
source and recompiling. This changes bench and dupecheck to take the circuit
file path as a required positional CLI argument instead.

• Add a clap-derived Cli with one positional input: PathBuf to each binary.
• clap was already a workspace dependency, so it is just added to the two
  crates' [dependencies]; no new dependency is introduced.
• No logic changes; START/NUM and the rest of each tool are untouched.

Usage:

bench <INPUT>
dupecheck <INPUT>

Type of Change

• Bug fix (non-breaking change which fixes an issue)

Notes to Reviewers

Per the issue, the remaining hardcoded paths were in util/bench and
util/dupecheck; this covers both.

Two disclosures:

• AI: I used Claude (Claude Code) to analyze the issue and author this patch,
  and to help draft this description. I reviewed the change myself.
• I did not build or run the test suite locally, so I am relying on CI to
  confirm formatting, clippy, and tests. The two checklist items about warnings
  and tests are left unchecked until CI verifies them.

I used a positional argument rather than an --input flag since there is a
single required input; happy to switch to a flag if you'd prefer.

Checklist

• I have performed a self-review of my code.
• I have commented my code where necessary.
• I have updated the documentation if needed.
• My changes do not introduce new warnings.
• I have added tests that prove my changes are effective or that my feature works.
• New and existing tests pass with my changes.

Related Issues

Closes #14