PRICE-01: migration note, and the tests drive the real control cycle

- DOCS: the migration note said markup and taxes do not matter; with the
  provider they are added to the wholesale price. Step 4 and 5 now say what
  they set and what static_profile does while no source has a price.
- The gap tests run the notification through cycle(), where the check is
  called, so a check that is never called goes red.
- test header: the real-transport checks are section 11.

Co-Authored-By: Claude <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bdqr7PiaHcBnzPituu2yTC

goodwe_controller/DOCS.md

@@ -2320,11 +2320,14 @@ Do this on the Configuration tab, in one save, and restart once:
 3. **Clear** **Current price entity** (`price_now_entity`) and **Average price
    entity** (`price_avg_entity`). The add-on refuses to start with a price
    source and these two together.
-4. Keep **Supplier markup** and **Distribution, levies and VAT** as they are
-   for a wholesale price. If the Home Assistant sensors already included them,
-   the figures were never in these two options, so nothing else changes.
+4. Check **Supplier markup** and **Distribution, levies and VAT**. With the
+   Home Assistant pair they decided nothing about the maintenance charge. With
+   the provider they are added to the wholesale price, so they set the prices
+   shown on the page and, if battery modes or trading are on, the prices those
+   decide on. The maintenance charge gate does not depend on them.
 5. Keep **Fixed or day/night tariff** (`static_profile`) if you have one. It
-   stays the fallback for trading when no source answers.
+   is still the tariff used, marked as estimated and without trading, while no
+   source has a price.
 6. Remove the `price_service` REST and template sensors from Home Assistant
    when you are satisfied. They are no longer read.