Salvages #23738 by @LeonSGP43. Wheel installs were missing skills/ and
optional-skills/ because pyproject's [tool.setuptools.packages.find]
only includes Python packages — the skills directories don't have
__init__.py so they were silently dropped from the wheel.
Adds setup.py with data_files spec emitting skills/* and optional-skills/*
under hermes_agent-<v>.data/data/, and a get_bundled_skills_dir() helper
in hermes_constants that discovers the wheel-installed location via
sysconfig before falling back to a source-checkout path. tools/skills_sync
uses the helper so 'hermes update' works for pip-installed users.
LeonSGP43