[verified] Fix bucket3 to rank by dividend yield (ignore score) — reviewer blocker

- allocate_capital _fill now takes sort_by; bucket3 uses dividend_yield, buckets 1/2 use combined_score
- Previously bucket3 wrongly ranked by score (picked CPN/PTT); now picks highest-yield CRC — matches user rule 'bucket3 = highest dividend yield, ignoring score'
- Added test_bucket3_ranks_by_yield_ignoring_score
- Re-reviewed (deleg_43b165e0) passed=true, no logic/security errors; full suite 185 OK

backend/tests/test_simulation.py

@@ -50,6 +50,25 @@ class AllocationTest(unittest.TestCase):
         overlap = set(bucket3_syms) & set(bucket1_syms)
         self.assertEqual(overlap, set())
 
+    def test_bucket3_ranks_by_yield_ignoring_score(self):
+        # The spec: bucket3 = highest dividend yield, IGNORING score.
+        # A low-score but high-yield name must rank above a high-score low-yield name.
+        cands = [
+            Candidate("HIGH_SCORE", 10.0, 8.0, True, 2.0),   # score 8, yield 2%
+            Candidate("HIGH_YIELD", 10.0, 0.1, True, 7.0),   # score 0.1, yield 7%
+            Candidate("MID", 10.0, 5.0, True, 3.0),
+        ]
+        # Big capital so bucket1 consumes only the top score name, leaving
+        # HIGH_YIELD (not HIGH_SCORE) to be the bucket3 top pick.
+        res = allocate_capital(1_000_000, cands)
+        b3 = [o.symbol for o in res.orders if o.bucket == 3]
+        # HIGH_YIELD (7%) should be selected in bucket3 before HIGH_SCORE (2%)
+        self.assertIn("HIGH_YIELD", b3)
+        if "HIGH_SCORE" in b3:
+            hi = b3.index("HIGH_SCORE")
+            hy = b3.index("HIGH_YIELD")
+            self.assertLess(hy, hi)
+
     def test_invalid_capital_raises(self):
         with self.assertRaises(Exception):
             allocate_capital(0, self.make_candidates())