docs: retire cron, record MQTT/discovery/gemma4 decisions

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

CONTEXT.md

@@ -7,7 +7,7 @@ Fetches unread articles from FreshRSS, selects and summarizes them via Ollama, t
 Forked from `Seth/PrinterAutomation` on Gitea.
 
 ## Components
-- `pos_briefing.py` — Main script. Run directly or via cron.
+- `pos_briefing.py` — Main script. Run directly or via the MQTT bridge (Google Home button).
 - `config.json` — Credentials and endpoints (not committed).
 - `config.example.json` — Template for config.json.
 
@@ -47,11 +47,12 @@ Forked from `Seth/PrinterAutomation` on Gitea.
 - **Uptime Kuma:** CT 147 — queried via `pct exec 147` (requires Proxmox host).
 - **This script runs on:** steel141 (`192.168.0.141`). Previously CT 166 (retired).
 
-## Cron
-Runs daily at 04:30 via crontab on steel141:
-```
-30 4 * * * python3 /root/bin/POS-Automation/pos_briefing.py >> /var/log/pos_briefing.log 2>&1
-```
+## Trigger
+On-demand only — **no cron**. Google Home button → HA `script.print_daily_briefing`
+→ MQTT `posbriefing/button/press` on broker CT 301 (192.168.0.154) →
+`pos-briefing-mqtt.service` on steel141 (systemd, `User=claude`) → `pos_briefing.py`
+→ printer discovered by MAC → ESC/POS over TCP. See `docs/ha-setup.md` and
+`docs/superpowers/specs/2026-06-07-ha-google-home-trigger-design.md`.
 
 ## Setup
 ```bash