UX-13 P0 review: keep unread keys, back off a failed entity read

- uimodel: editing a listed inverter keeps the stored flat keys, and a
  region of "own" keeps a stored price_taxes_profile (both were dropped).
- haentities: a failed read also waits CACHE_S, so polls while Home
  Assistant is down do not queue one 10 s read each.
- ui_text: the Flanders preset names its DSO, and the help says
  Wallonia and Brussels have no figures yet. REGION_PRESETS cites the card.
- tests: decode of a reversed solar row, both kept keys, the backoff.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

goodwe_controller/test_haentities.py

@@ -161,6 +161,24 @@ check("Home Assistant down after a good read: the old list, marked old",
       and len(_down["entities"]) == 4 and _down["age_s"] >= 30)
 check("...and peek() then gives nothing, so no warning rests on an old list",
       _cache.peek() is None)
+
+
+async def down_windows():
+    """One loop throughout: a contended asyncio.Lock binds to its loop."""
+    hass, clock = FakeHass(), Clock()
+    hass.answer = None
+    cache = E.EntityCache(hass, clock=clock)
+    counts = []
+    for step in (0, 1, 30):
+        clock.t += step
+        await asyncio.gather(*(cache.payload() for _ in range(5)))
+        counts.append(hass.reads)
+    return counts
+
+
+check("five polls while Home Assistant is down cost one read, the polls just "
+      "after wait for the next window, and that window tries once",
+      asyncio.run(down_windows()) == [1, 1, 2])
 _h2 = FakeHass()
 _h2.answer = None
 _empty = asyncio.run(E.EntityCache(_h2).payload("power"))