fix: Correct systemd configuration and Debian package setup

- Fix database update service to include config path parameter
- Move ConditionACPower from [Timer] to [Unit] section in timer config
- Add database directory to ReadWritePaths in main service
- Set explicit database path in Debian package config template
- Simplify postinst script to be quiet and use consistent skyview-adsb user
- Update README.Debian with comprehensive systemd service documentation
- Remove confusing dual-user setup in favor of single skyview-adsb user

SystemD Configuration Summary:
- Main service: skyview-adsb.service with database pre-update
- Database service: skyview-database-update.service (oneshot)
- Weekly timer: skyview-database-update.timer (Sunday 3AM with randomization)
- All services use skyview-adsb user consistently
- Database path: /var/lib/skyview-adsb/skyview.db
- Config path: /etc/skyview-adsb/config.json

🤖 Generated with [Claude Code](https://claude.ai/code)

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

debian/DEBIAN/postinst

@@ -18,20 +18,8 @@ case "$1" in
         chown skyview-adsb:skyview-adsb /var/lib/skyview-adsb /var/log/skyview-adsb >/dev/null 2>&1 || true
         chmod 755 /var/lib/skyview-adsb /var/log/skyview-adsb >/dev/null 2>&1 || true
         
-        # Create database directory for skyview user (not skyview-adsb)
-        mkdir -p /var/lib/skyview >/dev/null 2>&1 || true
-        if getent passwd skyview >/dev/null 2>&1; then
-            chown skyview:skyview /var/lib/skyview >/dev/null 2>&1 || true
-        else
-            # Create skyview user for database management
-            if ! getent group skyview >/dev/null 2>&1; then
-                addgroup --system --quiet skyview
-            fi
-            adduser --system --ingroup skyview --home /var/lib/skyview \
-                    --no-create-home --disabled-password --shell /bin/false --quiet skyview
-            chown skyview:skyview /var/lib/skyview >/dev/null 2>&1 || true
-        fi
-        chmod 755 /var/lib/skyview >/dev/null 2>&1 || true
+        # Database directory is managed by skyview-adsb user
+        # (Database path configured in /etc/skyview-adsb/config.json)
         
         # Set permissions on config files
         if [ -f /etc/skyview-adsb/config.json ]; then
@@ -55,18 +43,7 @@ case "$1" in
         fi
         
         # Initialize database on first install (but don't auto-enable timer)
-        if [ ! -f /var/lib/skyview/skyview.db ]; then
-            echo "Initializing SkyView database..."
-            sudo -u skyview /usr/bin/skyview-data update >/dev/null 2>&1 || true
-            echo "Database initialized with safe (public domain) data."
-            echo ""
-            echo "To enable automatic weekly updates:"
-            echo "  systemctl enable --now skyview-database-update.timer"
-            echo ""  
-            echo "To import additional data sources:"
-            echo "  skyview-data list"
-            echo "  skyview-data import <source>"
-        fi
+        sudo -u skyview-adsb /usr/bin/skyview-data -config /etc/skyview-adsb/config.json update >/dev/null 2>&1 || true
         ;;
 esac