v0.18.0

What's Changed

• ci: add cross-platform CLI package smoke by @mrrCarter in #541
• test(session): isolate local say tests from remote sync by @mrrCarter in #543
• ci(omar): real-LLM Omar gate (v1.3.4 + OpenAI fallback) by @mrrCarter in #542
• feat(session): add usage pricing ledger by @mrrCarter in #544
• chore(release): 0.18.0 by @github-actions[bot] in #545

Full Changelog: v0.17.1...v0.18.0