Adds hermes_cli/provider_catalog.py, deriving one descriptor per provider from
the CANONICAL_PROVIDERS universe (what `hermes model` renders, auto-extended
from provider plugins), joined with auth/env from PROVIDER_REGISTRY and display
metadata from ProviderProfile (with canonical/env fallbacks for the four
profile-less providers and the many profiles with blank display/signup fields).
Each descriptor is tagged with the desktop tab it belongs on (keys vs accounts)
by auth_type. This is the single source of truth the desktop Providers tabs will
derive membership from, so they can no longer drift from the CLI picker.
Tests assert the parity contract (catalog == hermes model universe) and tab
routing as invariants, not snapshots.
