Initial commit: EMS — Energie Management System

Complete self-consumption optimisation system for 7 kWp PV installation:
- Prometheus collector (grid power, SOC, PV, per-phase, compressor)
- Pure decision engine with SOC gates, hysteresis, priority ordering
- Shelly Gen1/Gen2 actuator (SHA-256 Digest auth, PM power readback)
- Viessmann OAuth2 client for DHW temperature control
- PV forecast integration (forecast.solar)
- Wallbox mutual exclusion (VX3 4.6 kW AC output constraint)
- Car-not-charging detection via Shelly PM
- Compressor idle → early SG-Ready release
- Per-phase grid power for single-phase wallbox decisions
- Manual override detection and web UI with override buttons
- Full unit test coverage for decision engine
- systemd service, Makefile, complete documentation

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

systemd/ems.service

@@ -0,0 +1,27 @@
+[Unit]
+Description=EMS — Energie Management System
+Documentation=https://github.com/tb/ems
+After=network-online.target
+Wants=network-online.target
+
+[Service]
+Type=simple
+ExecStart=/usr/local/bin/ems -config /etc/ems/ems-config.yaml
+Restart=on-failure
+RestartSec=30s
+
+# Creates /run/ems/ automatically (used for the heartbeat file)
+RuntimeDirectory=ems
+RuntimeDirectoryMode=0755
+
+# Logging
+StandardOutput=journal
+StandardError=journal
+SyslogIdentifier=ems
+
+# Basic hardening
+NoNewPrivileges=true
+PrivateTmp=true
+
+[Install]
+WantedBy=multi-user.target