OPT-27 round 3: a kept figure is at most 12 h old; DST-safe midnight bound; pruning test

F1: the evening rule has an age limit (KEPT_MAX_AGE_S).
F2: the evening bound is the next local midnight (_bounds), right on 25 h and 23 h days.
F5: test that old days are dropped from the stored hold.

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

goodwe_controller/app/solarfc.py

@@ -64,6 +64,9 @@ BELL_FROM_H, BELL_TO_H = 6.0, 20.0
 # OPT-27: a kept reading serves the night plan from the end of the bell until
 # this many hours after local midnight (the card: "local midnight + 3 h").
 KEPT_UNTIL_H = 3.0
+# OPT-27: and a reading older than this when used is not kept (a morning
+# figure must not drive the night).
+KEPT_MAX_AGE_S = 12 * 3600.0
 SAVE_EVERY_S = 900.0
 
 # Why there is no forecast (the page words are in ui_text `home_words`).
@@ -318,7 +321,8 @@ class Hold:
 
         The kept reading must be for `day0`, and either (a) at most `FRESH_S`
         old, or (b) used at night: from the end of the bell to local midnight,
-        or within `KEPT_UNTIL_H` after it. `kept` is true when (b) was needed,
+        or within `KEPT_UNTIL_H` after it, and then at most `KEPT_MAX_AGE_S`
+        old. `kept` is true when (b) was needed,
         or `as_today` (a tomorrow figure standing in for today, after
         midnight)."""
         rec = self._r.get((kind, entity, day0))
@@ -327,11 +331,12 @@ class Hold:
         day, at = rec
         if (now - at).total_seconds() <= FRESH_S and not as_today:
             return day, at, False
+        if (now - at).total_seconds() > KEPT_MAX_AGE_S:
+            return None
         # Both sides: a tomorrow sensor is asked with day0 = the next
         # midnight, which is in the future all day (round 2).
         after_midnight = day0 <= now < day0 + timedelta(hours=KEPT_UNTIL_H)
-        evening = _local_hour(now) >= BELL_TO_H and now < day0 + timedelta(
-            days=1)
+        evening = _local_hour(now) >= BELL_TO_H and now < _bounds(day0)[1]
         if as_today:
             return (day, at, True) if after_midnight else None
         return (day, at, True) if (evening or after_midnight) else None