[Tests]: Add end-to-end CLI smoke test (baseline -> compare) using examples/

Summary

Add a minimal end-to-end smoke test to validate the core CLI workflow: trace -> export JSON baseline -> export current -> compare.

Problem

There is no integration test that exercises the full CLI pipeline, so real workflows can break without being caught.

Proposed Solution

After examples/ exists (see #40), add a smoke test that:

1. Generates baseline.json
2. Generates current.json
3. Runs --compare baseline.json and asserts exit code + no crash + output files exist

Use tmp_path and subprocess.run.

Acceptance Criteria

• Smoke test runs in CI quickly
• Validates exit codes and output files
• Uses examples/ scripts as fixtures

Depends On

• #40 (examples/ directory)

Affected Files

• tests/
• examples/