fix: derive brewpi home from script location in service install

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01VsJfJngYUpB4dr77GvcEb8

deploy/brewpi.service

@@ -5,8 +5,8 @@ After=network.target
 [Service]
 Type=simple
 User=jens
-WorkingDirectory=/home/jens/work/repos/brewpi
-ExecStart=/home/jens/work/repos/brewpi/.venv/bin/python3 /home/jens/work/repos/brewpi/server/brewpi.py
+WorkingDirectory=${BREWPI_HOME}
+ExecStart=${BREWPI_HOME}/.venv/bin/python3 ${BREWPI_HOME}/server/brewpi.py
 Restart=on-failure
 RestartSec=5
 

deploy/install.sh

@@ -1,11 +1,13 @@
-#!/usr/bin/env bash
+  #!/usr/bin/env bash
 set -euo pipefail
 
 SERVICE=brewpi
-UNIT_FILE="$(dirname "$(realpath "$0")")/${SERVICE}.service"
+DEPLOY_DIR="$(dirname "$(realpath "$0")")"
+UNIT_FILE="${DEPLOY_DIR}/${SERVICE}.service"
 TARGET=/etc/systemd/system/${SERVICE}.service
 
-sudo cp "$UNIT_FILE" "$TARGET"
+export BREWPI_HOME="$(realpath "${DEPLOY_DIR}/..")"
+envsubst < "$UNIT_FILE" | sudo tee "$TARGET" > /dev/null
 sudo systemctl daemon-reload
 sudo systemctl enable "$SERVICE"
 echo "Installed. Start with: sudo systemctl start $SERVICE"