feat(spotify): wire setup wizard into 'hermes tools' + document cron usage (#15180)

A — 'hermes tools' activation now runs the full Spotify wizard.

Previously a user had to (1) toggle the Spotify toolset on in 'hermes
tools' AND (2) separately run 'hermes auth spotify' to actually use
it. The second step was a discovery gap — the docs mentioned it but
nothing in the TUI pointed users there.

Now toggling Spotify on calls login_spotify_command as a post_setup
hook. If the user has no client_id yet, the interactive wizard walks
them through Spotify app creation; if they do, it skips straight to
PKCE. Either way, one 'hermes tools' pass leaves Spotify toggled on
AND authenticated. SystemExit from the wizard (user abort) leaves the
toolset enabled and prints a 'run: hermes auth spotify' hint — it
does NOT fail the toolset toggle.

Dropped the TOOL_CATEGORIES env_vars list for Spotify. The wizard
handles HERMES_SPOTIFY_CLIENT_ID persistence itself, and asking users
to type env var names before the wizard fires was UX-backwards — the
point of the wizard is that they don't HAVE a client_id yet.

B — Docs page now covers cron + Spotify.

New 'Scheduling: Spotify + cron' section with two working examples
(morning playlist, wind-down pause) using the real 'hermes cron add'
CLI surface (verified via 'cron add --help'). Covers the active-device
gotcha, Premium gating, memory isolation, and links to the cron docs.

Also fixed a stale '9 Spotify tools' reference in the setup copy —
we consolidated to 7 tools in #15154.

Validation:
- scripts/run_tests.sh tests/hermes_cli/test_tools_config.py
    tests/hermes_cli/test_spotify_auth.py
    tests/tools/test_spotify_client.py
  → 54 passed
- website: node scripts/prebuild.mjs && npx docusaurus build
  → SUCCESS, no new warnings

website/docs/user-guide/features/spotify.md

@@ -12,20 +12,36 @@ Unlike Hermes' built-in OAuth integrations (Google, GitHub Copilot, Codex), Spot
 
 ## Setup
 
-### 1. Enable the toolset
+### One-shot: `hermes tools`
+
+The fastest path. Run:
 
 ```bash
 hermes tools
 ```
 
-Scroll to `🎵 Spotify`, press space to toggle it on, then `s` to save. The 9 Spotify tools only appear in the agent's toolset after this — they're off by default so users who don't want them don't ship extra tool schemas on every API call.
+Scroll to `🎵 Spotify`, press space to toggle it on, then `s` to save. Hermes drops you straight into the OAuth flow — if you don't have a Spotify app yet, it walks you through creating one inline. Once you finish, the toolset is enabled AND authenticated in one pass.
 
-### 2. Run the login wizard
+If you prefer to do the steps separately (or you're re-authing later), use the two-step flow below.
+
+### Two-step flow
+
+#### 1. Enable the toolset
+
+```bash
+hermes tools
+```
+
+Toggle `🎵 Spotify` on, save, and when the inline wizard opens, dismiss it (Ctrl+C). The toolset stays on; only the auth step is deferred.
+
+#### 2. Run the login wizard
 
 ```bash
 hermes auth spotify
 ```
 
+The 7 Spotify tools only appear in the agent's toolset after step 1 — they're off by default so users who don't want them don't ship extra tool schemas on every API call.
+
 If no `HERMES_SPOTIFY_CLIENT_ID` is set, Hermes walks you through the app registration inline:
 
 1. Opens `https://developer.spotify.com/dashboard` in your browser
@@ -153,6 +169,42 @@ Read-only tools work on Free accounts. Anything that mutates playback or the que
 | `spotify_albums` (all) | |
 | `spotify_library` (all) | |
 
+## Scheduling: Spotify + cron
+
+Because Spotify tools are regular Hermes tools, a cron job running in a Hermes session can trigger playback on any schedule. No new code needed.
+
+### Morning wake-up playlist
+
+```bash
+hermes cron add \
+  --name "morning-commute" \
+  "0 7 * * 1-5" \
+  "Transfer playback to my kitchen speaker and start my 'Morning Commute' playlist. Volume to 40. Shuffle on."
+```
+
+What happens at 7am every weekday:
+1. Cron spins up a headless Hermes session.
+2. Agent reads the prompt, calls `spotify_devices list` to find "kitchen speaker" by name, then `spotify_devices transfer` → `spotify_playback set_volume` → `spotify_playback set_shuffle` → `spotify_search` + `spotify_playback play`.
+3. Music starts on the target speaker. Total cost: one session, a few tool calls, no human input.
+
+### Wind-down at night
+
+```bash
+hermes cron add \
+  --name "wind-down" \
+  "30 22 * * *" \
+  "Pause Spotify. Then set volume to 20 so it's quiet when I start it again tomorrow."
+```
+
+### Gotchas
+
+- **An active device must exist when the cron fires.** If no Spotify client is running (phone/desktop/Connect speaker), playback actions return `403 no active device`. For morning playlists, the trick is to target a device that's always on (Sonos, Echo, a smart speaker) rather than your phone.
+- **Premium required for anything that mutates playback** — play, pause, skip, volume, transfer. Read-only cron jobs (scheduled "email me my recently played tracks") work fine on Free.
+- **The cron agent inherits your active toolsets.** Spotify must be enabled in `hermes tools` for the cron session to see the Spotify tools.
+- **Cron jobs run with `skip_memory=True`** so they don't write to your memory store.
+
+Full cron reference: [Cron Jobs](./cron).
+
 ## Sign out
 
 ```bash