fix: resolve 3 MEDIUM code review findings

M1: Cache confusion-pair confidences in Path B (eliminate redundant
    resolve_confusion_pair re-calls in _path_rule_engine)
M2: Resolve contradictions in Path C instead of hardcoding
    resolved_count=0 in _path_llm_assisted
M4: Add DIVIDE_25 to contradiction pair coverage (50-25, 100-25)
    and update test_contradiction_pairs_defined to verify all 3 variants

tests/hina/test_rule_engine.py

@@ -327,15 +327,26 @@ def test_resolve_contradiction_csv():
 # ═══════════════════════════════════════════════════════════════════════════
 
 def test_contradiction_pairs_defined():
-    """CONTRADICTION_PAIRS 包含所有 8 个混淆对"""
-    assert len(CONTRADICTION_PAIRS) == 8
-    names = {p["name"] for p in CONTRADICTION_PAIRS}
-    expected = {
+    """CONTRADICTION_PAIRS 包含所有混淆对，DIVIDE 全部 3 种变体"""
+    assert len(CONTRADICTION_PAIRS) >= 8
+    pairs_by_name: dict[str, list[dict]] = {}
+    for p in CONTRADICTION_PAIRS:
+        pairs_by_name.setdefault(p["name"], []).append(p)
+
+    expected_names = {
         "matching_vs_keybreak", "dedup_vs_nodedup", "validation_vs_keybreak",
         "csv_merge_vs_split", "simple_vs_two_stage", "pure_vs_mixed",
         "division_50_25_100", "mn_output_mode",
     }
-    assert names == expected
+    assert set(pairs_by_name.keys()) >= expected_names
+
+    # division 应有 3 个矛盾对 (50-100, 50-25, 100-25) 覆盖所有变体
+    div_pairs = pairs_by_name.get("division_50_25_100", [])
+    assert len(div_pairs) == 3, f"DIVIDE 应覆盖全部 3 组变体，当前 {len(div_pairs)} 组"
+    div_types = {(p["type_a"], p["type_b"]) for p in div_pairs}
+    assert ("DIVIDE_50", "DIVIDE_100") in div_types
+    assert ("DIVIDE_50", "DIVIDE_25") in div_types
+    assert ("DIVIDE_100", "DIVIDE_25") in div_types
 
 
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