Fixes #1973

Summary

Fresh installs that use uv pip install -e ".[all]" or uv pip install -e ".[all,dev]" do not install Matrix support, even though Matrix can be configured in hermes gateway setup.

The matrix extra is defined in pyproject.toml, but it was not included in the all extra. As a result, a fresh install can collect Matrix credentials successfully, but gateway startup still fails with:

Matrix: matrix-nio not installed. Run: pip install 'matrix-nio[e2e]'

Fix

Added hermes-agent[matrix] to the all extra in pyproject.toml.

This keeps Matrix as an optional extra for targeted installs, while making the default full install match the behavior implied by the setup flow and install docs.

Tests

Added tests/test_project_metadata.py::test_all_extra_includes_matrix_dependency to prevent the matrix extra from being dropped from all again.

Verified under Python 3.11:

/tmp/hermes311/bin/python -m pytest -o addopts='' tests/test_project_metadata.py -q
# 1 passed

Also re-checked the existing .[all] update/install path tests:

/tmp/hermes311/bin/python -m pytest -o addopts='' tests/hermes_cli/test_update_autostash.py -q
# 13 passed