OPT-11 P1 review: a mode never beats the peak floor; SAFETY-03 kept at the rail

- arbiter: a mode now gives way only as far as a site limit above P_MODE
  needs (_unit_modes at N>1, _site_mode at N=1). Before, the modes were
  released only when the peak floor bound S, so a trade won above the floor
  kept them and placed less than the floor (an Off battery at N=1 went to 0 W
  under a 2000 W floor), and a capped grid charge released an Off battery.
  While released, held batteries weigh 0 and carry only the shortfall.
- control: a side of the loop bound that reaches the rail is left to the
  rail, so SAFETY-03's i_clamped still fires with every battery on.
- opt11_identity: add maintenance scenarios and a 6000-case arbiter digest
  (peak floor, trades, maintenance, refusals); a5dddad digests pinned.
- tests: test_arbiter part 11, test_control (g), test_modes (0/1 refused,
  loop bound counts live units only). DOCS and DECISIONS say the new rule.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01UBtqPrG1mDLXzTEBnhEkkV

goodwe_controller/app/allocator.py

@@ -304,9 +304,9 @@ def unit_interval(b, deciding_priority=None):
     """OPT-11. `(lo, hi, note)`: the interval a unit is allocated into.
 
     The hard limits (`b.lo`, `b.hi`) always apply. The unit's MODE range
-    (`b.mode_lo`, `b.mode_hi`) narrows them only when the site target was
-    decided at or below the mode's own priority - `deciding_priority` None
-    means no higher claim was named, so the mode applies. `note` says why the
+    (`b.mode_lo`, `b.mode_hi`) narrows them unless `deciding_priority` is
+    above the mode's own priority (arbiter._unit_modes() passes None when the
+    modes hold, and the yielding limit's priority when they give way). `note` says why the
     mode did not apply, or is None when it did or there is none:
 
     * MODE_FAULT: the mode range leaves out 0 W. A mode may forbid a direction