SAFETY-86: peak guard outranks the maintenance hold

During a HOLD the holding battery gives what keeps the quarter at the peak
aim. N=1: the peak floor is refiled at P_MAINTENANCE, as for a drain
(SAFETY-83). N>=2: the hold's pin is raised to the floor minus what the
other live batteries may place, so they give first. A site stop still
decides alone. The hold ends on its clock even if the level dipped.
Below the aim nothing changes (rows identical).

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

goodwe_controller/app/arbiter.py

@@ -79,7 +79,7 @@ P_PEAK = 50           # capacity-tariff peak shaving - costs real money
 # The order in effect: safety limits and the SAFETY-73 refusal > the peak
 # guard > maintenance > modes > trade > loop. A peak floor above a drain still
 # binds: the `drain` site floor at N>=2 (SAFETY-78), refiled at P_MAINTENANCE
-# at N=1 (SAFETY-83). Not a maintenance HOLD at N=1 (DECISIONS/SAFETY-83).
+# at N=1 (SAFETY-83); over a HOLD, `_peak_over_hold()` (SAFETY-86).
 # A cheap-window charge is suspended while the peak guard holds and, at N>=2,
 # sized to the quarter's headroom (SAFETY-84).
 P_MAINT_SHAPE = 40    # maintenance shaping the loop (charge-only)