fix(rules): use the attacker's best corner for cover bonus

SRD 'Cover': 'To determine whether your target has cover from your ranged attack, choose a corner of your square.' The ranged scorer in cover_bonus_cells took the MAX over all attacker corners (worst corner); the cover gate has_cover_cells and RAW use the attacker's best corner. Ranged cells are now scored min over attacker corners of (max over target-corner lines), then min over attacker cells - the bonus can no longer exceed what the gate admits. Melee keeps the worst-corner rule ('any line from ANY corner of your square'). Updated the two pins that locked the old worst-corner scores.

Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)

Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>

src/pf1e_simulator/los.py

@@ -293,10 +293,16 @@ def cover_bonus_cells(
     )
     # PF1e CRB "Cover", rule of corners: the attacker chooses the corner (and,
     # for a multi-square creature, the occupied square) that gives it the best
-    # shot, so it suffers only the MINIMUM cover over its own cells. The
-    # target side follows the same choice rule: RAW checks ANY line to ANY
-    # corner of the (chosen) square, scored by the MAXIMUM over corner lines —
-    # union over all target cells for ranged, best single cell for melee.
+    # shot, so it suffers only the MINIMUM cover over its own cells. Ranged:
+    # "choose a corner of your square. If any line from this corner to any
+    # corner of the target's square passes through cover, the target has
+    # cover" — each attacker corner is scored by the MAXIMUM over the target's
+    # corner lines (union over all target cells), and the attacker picks its
+    # BEST corner: MIN over attacker corners. Melee: the attacker may also
+    # pick any single square of a multi-square target (CRB "Big Creatures and
+    # Cover"), so the target side is a MIN over cells; the attacker side
+    # stays the worst-corner rule ("any line from ANY corner of your
+    # square").
     per_cell_best = (
         min(
             max(
@@ -307,11 +313,13 @@ def cover_bonus_cells(
             for cell_t in target_cells
         )
         if not ranged
-        else max(
-            lines.bonus(corner_a, corner_t)
+        else min(
+            max(
+                lines.bonus(corner_a, corner_t)
+                for cell_t in target_cells
+                for corner_t in _corners(cell_t)
+            )
             for corner_a in _corners(cell_a)
-            for cell_t in target_cells
-            for corner_t in _corners(cell_t)
         )
         for cell_a in attacker_cells
     )