chore(tests): move oceanbase peewee test under test/ and fix enum check (#12969)

### What problem does this PR solve?

This mistake was made by PR #12926 
This PR makes the OceanBase peewee unit test discoverable by the default
unit test runner/CI (by moving it under test/), so it’s included in the
unified unit test suite.
It also fixes `test_database_lock_enum_values` to correctly handle Enum
alias members (DatabaseLock uses the same value for MYSQL and
OCEANBASE).

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [ ] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):

### Screenshots
The original `test_oceanbase_peewee.py` was placed under tests/, which
isn’t included in the default unit test runner’s testpaths, so it wasn’t
picked up by the unit test suite. So we need to move it to correct path.
<img width="670" height="540" alt="image"
src="https://github.com/user-attachments/assets/69d39346-450f-46dc-8965-29c3d7b32bc9"
/>

When using old version in `test_oceanbase_peewee.py`:
```
    def test_database_lock_enum_values(self):
        """Test DatabaseLock enum has all expected values."""
        expected = {'MYSQL', 'OCEANBASE', 'POSTGRES'}
        actual = {e.name for e in DatabaseLock}
        assert expected.issubset(actual), f"Missing: {expected - actual}"
```
The old check iterated Enum members, so alias values were skipped and
only `MYSQL/POSTGRES` were seen, making OCEANBASE appear missing.

<img width="1998" height="931" alt="65e2837f23b7b298980a410c7d5c2f09"
src="https://github.com/user-attachments/assets/d8e98c5a-2cfa-4182-ae35-a3ef03554a27"
/>

and new version uses `DatabaseLock.__members__` and passes:
<img width="2024" height="1170" alt="1aa8c6facb28d24149270fe1bc4a9dd9"
src="https://github.com/user-attachments/assets/d8688936-ccac-4a39-a389-23dc6f0fe276"
/>

test/unit_test/utils/test_oceanbase_peewee.py

@@ -0,0 +1,126 @@
+"""
+Tests for OceanBase Peewee ORM support.
+"""
+
+import pytest
+from api.db.db_models import (
+    RetryingPooledOceanBaseDatabase,
+    PooledDatabase,
+    DatabaseLock,
+    TextFieldType,
+)
+
+
+class TestOceanBaseDatabase:
+    """Test cases for OceanBase database support."""
+
+    def test_oceanbase_database_class_exists(self):
+        """Test that RetryingPooledOceanBaseDatabase class exists."""
+        assert RetryingPooledOceanBaseDatabase is not None
+
+    def test_oceanbase_in_pooled_database_enum(self):
+        """Test that OCEANBASE is in PooledDatabase enum."""
+        assert hasattr(PooledDatabase, 'OCEANBASE')
+        assert PooledDatabase.OCEANBASE.value == RetryingPooledOceanBaseDatabase
+
+    def test_oceanbase_in_database_lock_enum(self):
+        """Test that OCEANBASE is in DatabaseLock enum."""
+        assert hasattr(DatabaseLock, 'OCEANBASE')
+
+    def test_oceanbase_in_text_field_type_enum(self):
+        """Test that OCEANBASE is in TextFieldType enum."""
+        assert hasattr(TextFieldType, 'OCEANBASE')
+        # OceanBase should use LONGTEXT like MySQL
+        assert TextFieldType.OCEANBASE.value == "LONGTEXT"
+
+    def test_oceanbase_database_inherits_mysql(self):
+        """Test that OceanBase database inherits from PooledMySQLDatabase."""
+        from playhouse.pool import PooledMySQLDatabase
+        assert issubclass(RetryingPooledOceanBaseDatabase, PooledMySQLDatabase)
+
+    def test_oceanbase_database_init(self):
+        """Test OceanBase database initialization."""
+        db = RetryingPooledOceanBaseDatabase(
+            "test_db",
+            host="localhost",
+            port=2881,
+            user="root",
+            password="password",
+        )
+        assert db is not None
+        assert db.max_retries == 5  # default value
+        assert db.retry_delay == 1  # default value
+
+    def test_oceanbase_database_custom_retries(self):
+        """Test OceanBase database with custom retry settings."""
+        db = RetryingPooledOceanBaseDatabase(
+            "test_db",
+            host="localhost",
+            max_retries=10,
+            retry_delay=2,
+        )
+        assert db.max_retries == 10
+        assert db.retry_delay == 2
+
+    def test_pooled_database_enum_values(self):
+        """Test PooledDatabase enum has all expected values."""
+        expected = {'MYSQL', 'OCEANBASE', 'POSTGRES'}
+        actual = {e.name for e in PooledDatabase}
+        assert expected.issubset(actual), f"Missing: {expected - actual}"
+
+    def test_database_lock_enum_values(self):
+        """Test DatabaseLock enum has all expected values."""
+        expected = {'MYSQL', 'OCEANBASE', 'POSTGRES'}
+        actual = set(DatabaseLock.__members__.keys())
+        assert expected.issubset(actual), f"Missing: {expected - actual}"
+
+
+class TestOceanBaseConfiguration:
+    """Test cases for OceanBase configuration via environment variables."""
+
+    def test_settings_default_to_mysql(self):
+        """Test that default DB_TYPE is mysql."""
+        import os
+        # Save original value
+        original = os.environ.get('DB_TYPE')
+        
+        try:
+            # Remove DB_TYPE to test default
+            if 'DB_TYPE' in os.environ:
+                del os.environ['DB_TYPE']
+            
+            # Reload settings
+            from common import settings
+            settings.DATABASE_TYPE = os.getenv("DB_TYPE", "mysql")
+            
+            assert settings.DATABASE_TYPE == "mysql"
+        finally:
+            # Restore original value
+            if original:
+                os.environ['DB_TYPE'] = original
+
+    def test_settings_can_use_oceanbase(self):
+        """Test that DB_TYPE can be set to oceanbase."""
+        import os
+        # Save original value
+        original = os.environ.get('DB_TYPE')
+        
+        try:
+            os.environ['DB_TYPE'] = 'oceanbase'
+            
+            # Reload settings
+            from common import settings
+            settings.DATABASE_TYPE = os.getenv("DB_TYPE", "mysql")
+            
+            assert settings.DATABASE_TYPE == "oceanbase"
+        finally:
+            # Restore original value
+            if original:
+                os.environ['DB_TYPE'] = original
+            else:
+                if 'DB_TYPE' in os.environ:
+                    del os.environ['DB_TYPE']
+
+
+if __name__ == "__main__":
+    pytest.main([__file__, "-v"])