Improvements and fixes

The phone is no longer signed out after a day, the SEPA confirmation e-mail delivers its PDF, and outages read as the meters say.

• The organization's "Contract" tab is visible to contract administrators again.
• The outage report now gives each combiner box and string its own column under the inverter.
• The battery dashboard now shows the rack-level cell voltage and temperature minimums and maximums when box-level cell data is missing.
• Plant subnets in a reserved VPN address range are refused where they are entered, naming the range and way out.