Fix MAP vs STRUCT type test categorization

- Move numeric key test from STRUCT to MAP (correct type)
- Update SQLAlchemy reflection test expectations for MAP conversion
- Add proper STRUCT test with named fields
- Ensure tests match the actual data type semantics

{1=2, 3=4} is MAP format, not STRUCT format.

🤖 Generated with [Claude Code](https://claude.ai/code)

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

Author: laughingman7743

tests/pyathena/sqlalchemy/test_base.py

@@ -255,7 +255,7 @@ def test_reflect_select(self, engine):
             date(2017, 1, 2),
             b"123",
             "[1, 2]",
-            "{1=2, 3=4}",  # map type remains as string
+            {"1": 2, "3": 4},  # map type now converted to dict
             {"a": 1, "b": 2},  # row type now converted to dict
             Decimal("0.1"),
         ]

tests/pyathena/test_converter.py

@@ -101,14 +101,24 @@ def test_to_struct_athena_complex_cases():
         )
 
 
-def test_to_struct_athena_numeric_keys():
-    """Test Athena struct with numeric keys (like maps)"""
-    struct_value = "{1=2, 3=4}"
-    result = _to_struct(struct_value)
+def test_to_map_athena_numeric_keys():
+    """Test Athena map with numeric keys"""
+    from pyathena.converter import _to_map
+
+    map_value = "{1=2, 3=4}"
+    result = _to_map(map_value)
     expected = {"1": 2, "3": 4}
     assert result == expected
 
 
+def test_to_struct_named_fields():
+    """Test Athena struct with named fields"""
+    struct_value = "{name=John, age=30}"
+    result = _to_struct(struct_value)
+    expected = {"name": "John", "age": 30}
+    assert result == expected
+
+
 def test_to_struct_empty_string():
     result = _to_struct("")
     assert result is None