MAINT-13 round 3: provider site, hourly fixed-tariff check, faster tests

- A price-provider site with no fixed tariff is not a gate (its plan never
  sets `cheap`); DECISIONS §3 says so and a test pins it.
- The fixed-tariff check is worked out once an hour, not every tick.
- test_maint13: run() steps really are `step` minutes; the long loops use
  5-minute steps (the per-tick cap); wall backstop checked "not before".
- test_safety93: the drain bound is the rig's configured drain rate.

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

goodwe_controller/app/main.py

@@ -1189,6 +1189,7 @@ class Controller:
         self.peak_fc = None
         self.cheap = False
         self._price_gated = False     # MAINT-13: is a price gate set up
+        self._gated_key = None        # MAINT-13: (options, hour) of the cache
         # TARIFF-03. One line of prose for the status page saying WHICH tariff
         # window we are in and why it is or is not cheap - so "Cheap window:
         # no" is an evidenced answer rather than a bare no.
@@ -3337,9 +3338,9 @@ class Controller:
             # ⚠️ AND IT CANNOT BE BOTH. validate.py refuses static_profile
             # alongside the two Home Assistant entities, because this `if` picks
             # one and the loser is silent.
-            self.cheap, self.tariff_words = static_status(
-                o, datetime.now(timezone.utc))
-            self._price_gated = static_gated(o, datetime.now(timezone.utc))
+            _now = datetime.now(timezone.utc)
+            self.cheap, self.tariff_words = static_status(o, _now)
+            self._price_gated = self._static_gated(o, _now)
 
         # ⚠️ TARIFF-11. THE PROVIDER PLAN REACHES THE *Tariff* ROW HERE, AND
         # THIS IS THE ONLY PLACE THE TWO SOURCES MEET. Everything above is the
@@ -3878,6 +3879,16 @@ class Controller:
                            inv.refusal_note())]
                 if n]
 
+    def _static_gated(self, o: dict, now: datetime) -> bool:
+        """`static_gated()`, worked out once an hour: it builds the same
+        month-long plan as `static_status()` (about 20 ms with a profile), and
+        whether a fixed tariff is set up does not change from tick to tick
+        (options change only with a restart)."""
+        key = (id(o), now.strftime("%Y-%m-%d %H"))
+        if key != self._gated_key:
+            self._gated_key, self._gated = key, static_gated(o, now)
+        return self._gated
+
     def _charge_gate_open(self, inv) -> bool:
         """MAINT-13: may this pack charge now, for the maintenance timeout?