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/test_safety93.py

@@ -265,13 +265,17 @@ check("timeout with B due: the charge ends at 1780 s and A is not restarted",
       and c.maints[0].phase == IDLE
       and c.maints[0].backoff_until(rig.BASE + timedelta(seconds=1800))
       is not None)
+# A command below 0 W is a charge, so B's commands must stay at or above 0;
+# the drain rate is the one this rig's controller was configured with.
+drain_w = c.maints[1].cfg.discharge_w
+print(f"    B drain rate configured on the rig: {drain_w:.0f} W")
 check("⭐ timeout with B due: no battery charges from the grid after it",
       charging_hi(rows, 1780, 1798, hi1) == 0
       and min(cmd(r)["b"] for r in rows if r[0] >= 1780) >= 0.0)
 check("...B takes the slot and begins its own drain, which is the only large "
-      "step, to the drain rate and no higher",
+      "step, to the configured drain rate and no higher",
       c.maints[1].phase == DRAIN
-      and max(cmd(r)["b"] for r in rows if r[0] >= 1780) <= 2000.0
+      and max(cmd(r)["b"] for r in rows if r[0] >= 1780) <= drain_w
       and moves(rows, "a", 1780, 1798) <= SLEW)
 
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