MAINT-13 round 2: gate open when nothing holds the charge back; safety93 scenario restored

- gate_open is true with no price gate set up, in a cheap window, or while the
  pack is taking charge; the stall rule and timeout now work on a no-tariff site.
- reset the save timer on a phase change; exact 5 min gap-cap test.
- test_safety93: original timeout scenario kept (B finished) plus a case where a
  due B takes the slot after A's failure.

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Bdqr7PiaHcBnzPituu2yTC

goodwe_controller/app/main.py

@@ -3875,6 +3875,22 @@ class Controller:
                            inv.refusal_note())]
                 if n]
 
+    def _charge_gate_open(self, inv) -> bool:
+        """MAINT-13: may this pack charge now, for the maintenance timeout?
+
+        True when no price gate is set up (no price entities, no fixed tariff:
+        nothing holds the charge back), in a cheap window, or while the pack is
+        really taking charge (sun outside cheap hours). Closed only when a gate
+        exists, it is shut, and the pack is not charging.
+        """
+        o = self.o
+        gated = bool((o.get("price_now_entity") and o.get("price_avg_entity"))
+                     or o.get("static_profile"))
+        if not gated or self.cheap:
+            return True
+        batt = inv.batt
+        return batt is not None and float(batt) <= -MAINT_CHARGING_W
+
     async def cycle(self) -> None:
         """Gather claims, resolve precedence, write the winner.
 
@@ -3923,10 +3939,10 @@ class Controller:
             if blocked is None:
                 maint_results.append(MaintResult(IDLE, False, None, False, []))
                 continue
-            # MAINT-13: the charge timeout counts only the minutes the price
-            # gate (`self.cheap`) let the pack charge.
+            # MAINT-13: the charge timeout counts only the minutes the pack was
+            # allowed to charge (see `_charge_gate_open`).
             res = machine.tick(now, inv.soc, blocked_by=blocked,
-                               gate_open=bool(self.cheap))
+                               gate_open=self._charge_gate_open(inv))
             for msg in res.events:
                 self.log_event(msg, hint=messages.hint(
                     "maint_failed" if res.failed else "maintenance",
@@ -7387,6 +7403,10 @@ class Controller:
         return None
 
 
+# MAINT-13: a battery power reading at or below minus this many W is a pack
+# that is taking charge.
+MAINT_CHARGING_W = 50.0
+
 # SAFETY-61. Exit status when the control task dies; 70 is sysexits(3)
 # EX_SOFTWARE. See DECISIONS/SAFETY-61-control-task-death.md.
 EXIT_CONTROL_DIED = 70