fix: forward stdin through npm launcher

[cafitac]

Summary

• Forward stdin from the npm launcher into the delegated Python CLI process.
• Add a real Hermes hook regression test that proves node bin/agent-memory.js hermes-pre-llm-hook ... receives hook JSON from stdin.
• Extend published install smoke to exercise stdin-dependent hermes-pre-llm-hook through npm exec, uvx, and pipx surfaces so future releases QA the Hermes hook path after publish.

Test Plan

• uv run pytest tests/test_npm_launcher.py tests/test_published_install_smoke.py -q
• uv run pytest tests/ -q
• uv run python scripts/check_release_metadata.py
• uv run python scripts/smoke_release_readiness.py
• npm pack --dry-run
• git diff --check
• node --check bin/agent-memory.js
• static diff scan: 0 findings