Add WiFi and HDMI power saving features for remote sensors

Implements power saving optimizations to extend battery life on solar-powered remote air quality sensors:

- WiFi Power Saving: Disable WiFi 10 minutes after boot to save ~100-200mA
  - Configurable via web UI checkbox in admin panel
  - WiFi automatically re-enables after reboot for 10-minute configuration window
  - Systemd timer (nebuleair-wifi-powersave.timer) manages automatic disable
  - New wifi/power_save.py script checks database config and disables WiFi via nmcli

- HDMI Disable: Added hdmi_blanking=2 to boot config to save ~20-30mA
  - Automatically configured during installation

- Database: Added wifi_power_saving boolean config (default: disabled)
  - Uses INSERT OR IGNORE for safe updates to existing installations

- UI: Added checkbox control in admin.html for WiFi power saving
  - Includes helpful description of power savings and behavior

- Services: Updated setup_services.sh and update_firmware.sh to manage new timer

Total power savings: ~120-230mA when WiFi power saving enabled

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

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

update_firmware.sh

@@ -73,6 +73,7 @@ sudo chmod 755 /var/www/nebuleair_pro_4g/BME280/*.py
 sudo chmod 755 /var/www/nebuleair_pro_4g/SARA/*.py
 sudo chmod 755 /var/www/nebuleair_pro_4g/envea/*.py
 sudo chmod 755 /var/www/nebuleair_pro_4g/MPPT/*.py 2>/dev/null
+sudo chmod 755 /var/www/nebuleair_pro_4g/wifi/*.py 2>/dev/null
 check_status "File permissions update"
 
 # Step 4: Restart critical services if they exist
@@ -87,6 +88,7 @@ services=(
     "nebuleair-bme280-data.timer"
     "nebuleair-mppt-data.timer"
     "nebuleair-noise-data.timer"
+    "nebuleair-wifi-powersave.timer"
 )
 
 for service in "${services[@]}"; do