On macOS with Homebrew (Apple Silicon), Node.js and agent-browser
binaries live under /opt/homebrew/bin/ which is not included in the
_SANE_PATH fallback used by browser_tool.py and environments/local.py.
When Hermes runs with a filtered PATH (e.g. as a systemd service),
these binaries are invisible, causing 'env: node: No such file or
directory' errors when using browser tools.
Changes:
- Add /opt/homebrew/bin and /opt/homebrew/sbin to _SANE_PATH in both
browser_tool.py and environments/local.py
- Add _discover_homebrew_node_dirs() to find versioned Node installs
(e.g. brew install node@24) that aren't linked into /opt/homebrew/bin
- Extend _find_agent_browser() to search Homebrew and Hermes-managed
dirs when agent-browser isn't on the current PATH
- Include discovered Homebrew node dirs in subprocess PATH when
launching agent-browser
- Add 11 new tests covering all Homebrew path discovery logic