SAFETY-125 round 2: the one-inverter maintenance charge is sized to the room too

Owner 2026-10-29: fix N=1 in this hotfix. _charge_headroom() no longer
returns early at one inverter, so the N=1 cheap-window maintenance charge
is held to charge_room_w() as at N=2; SAFETY-84's site-stop rule stays N>=2
only (at N=1 such a stop outranks the shaping anyway). The guard no longer
steps in and gives power at each quarter's end during that charge.

test_safety125.py: N=1 maintenance on 5 s and 10 s meters with late
readings, with and without a banked peak; the row in an N=2 maintenance
charge and in shadow mode; edge cases (blind past the hold, a start
mid-quarter, the summer-time change, the forecast in W, a 10 s meter, the
last second). test_safety84/87: three N=1 pins move. test_safety119: its
quarter-edge hand-back runs keep the old N=1 sizing as a fixture, plus a
check that with the new sizing nothing hands back. CHANGELOG, DECISIONS,
DOCS follow.

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

goodwe_controller/app/main.py

@@ -3232,14 +3232,14 @@ class Controller:
         return floor
 
     def _charge_headroom(self, floor: float, claims) -> float:
-        """SAFETY-84: at N>=2 a cheap-window charge pulls no more than the
-        quarter's headroom under the peak aim (`charge_headroom_w()`), so it
-        yields just enough to the peak guard, and nothing under a site stop
-        (its 0 W would need the other pack to give). N=1 is unchanged."""
-        if len(self.inverters) < 2:
-            return floor
-        if any(c.kind == SET and c.actuator == ACTUATOR_SITE
-               and c.priority > P_MAINT_SHAPE for c in claims):
+        """SAFETY-84: a cheap-window charge pulls no more than the quarter's
+        room under the peak aim (`charge_room_w()`), so it yields just enough
+        to the peak guard; at N>=2 nothing under a site stop (its 0 W would
+        need the other pack to give). SAFETY-125: at N=1 too, owner
+        2026-10-29; the stop rule stays N>=2 only."""
+        if len(self.inverters) > 1 and any(
+                c.kind == SET and c.actuator == ACTUATOR_SITE
+                and c.priority > P_MAINT_SHAPE for c in claims):
             return 0.0
         room = peakguard.charge_room_w(self.peak_guard, self._peak_proj)
         floor = floor if room is None else min(floor, room)