feat(dao): add robust generic list and count methods to BaseDAO with full test coverage

- Introduced generic `list` and `count` methods to BaseDAO for consistent querying and counting across all DAOs.
- Both methods support filtering (including IN queries), ordering, pagination, search across columns, custom FAB-style filters, and always-on base filters.
- Added comprehensive unit tests for `list` and `count` in `tests/unit_tests/dao/base_test.py`, covering:
  - Filtering (including boolean, None, and IN queries)
  - Ordering (asc/desc, multiple columns)
  - Pagination (including out-of-range)
  - Search across columns
  - Custom filter logic
  - Always-on base filter logic
  - Edge cases and skip_base_filter
- Moved common test fixtures to `conftest.py` for reuse.

tests/unit_tests/dao/conftest.py

@@ -0,0 +1,36 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+
+import pytest
+from flask_appbuilder.security.sqla.models import User
+
+
+@pytest.fixture
+def user_with_data(session):
+    User.metadata.create_all(session.get_bind())
+    user = User(
+        id=101,
+        username="testuser",
+        first_name="Test",
+        last_name="User",
+        email="testuser@example.com",
+        active=True,
+    )
+    session.add(user)
+    session.commit()
+    yield session
+    session.rollback()