charge_tracker: Migrate to 32 byte tracked charge entries. Then implement:

[rtrbt]

• Flags byte/int
  • Entry is deleted
  • Start/Continuation (f.e. price change)
  • [...]
• Electricity price (See #328)
  • If price changes during a charge, track a stop and a start
• Charge duration (accumulate time between B/C and C/B transitions)
• NFC-Tag-ID+Type?

[rtrbt]

When this is done, add an automation action that sets the electricity price. This action can be used for day/night rates.