DatumRawQuery class

An adapter-aware raw query for projections, aggregations, and joins that bypass full entity hydration (#11).

Unlike DatumQuery (which returns hydrated entities), a raw query returns raw rows (List<Map<String, dynamic>>) so screens can select specific columns or compute COUNT/SUM/GROUP BY without materializing models.

It carries fields for both worlds; each adapter reads the ones it supports:

// Local SQL adapter (e.g. Drift/SQLite):
final rows = await manager.rawQuery(
  const DatumRawQuery(sql: 'SELECT id, name FROM users WHERE age > ?', args: [18]),
  source: DataSource.local,
);

// Remote adapter (e.g. Supabase/REST):
final rows = await manager.rawQuery(
  const DatumRawQuery(table: 'users', select: 'id, name', filters: {'age': {'gt': 18}}),
  source: DataSource.remote,
);