Follow-up on top of #15096 cherry-pick:
- Remove spotify_* from _HERMES_CORE_TOOLS (keep only in the 'spotify'
toolset, so the 9 Spotify tool schemas are not shipped to every user).
- Add 'spotify' to CONFIGURABLE_TOOLSETS + _DEFAULT_OFF_TOOLSETS so new
installs get it opt-in via 'hermes tools', matching homeassistant/rl.
- Wire TOOL_CATEGORIES entry pointing at 'hermes auth spotify' for the
actual PKCE login (optional HERMES_SPOTIFY_CLIENT_ID /
HERMES_SPOTIFY_REDIRECT_URI env vars).
- scripts/release.py: map contributor email to GitHub login.