Add systemd units

Each repo carries the units for the daemons it owns. WorkingDirectory stays
/srv/astrape so env/ and models/ resolve, while the code comes from the
editable installs under repos/.

The old astrape-db.service was misnamed -- it runs the weather forecast
ingest, and collided with what would have been an astrape-db repo. It is
astrape-weather-forecast.service here.

The training unit forces ATEN_CPU_CAPABILITY=default, because this host has no
AVX2 and torch otherwise dies with SIGILL in Adam, and caps threads with Nice
so a nightly run does not starve the 5-second Modbus poll.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

deploy/systemd/astrape-usage-tcn-training.timer

@@ -0,0 +1,11 @@
+[Unit]
+Description=Run Astrape Usage TCN Adaptive Training Nightly
+
+[Timer]
+OnCalendar=*-*-* 03:20:00
+Persistent=true
+RandomizedDelaySec=20m
+Unit=astrape-usage-tcn-training.service
+
+[Install]
+WantedBy=timers.target