✨ feat(sync): add data consistency compare (count + ID-set)

src/sync/sql_writer.py

@@ -143,6 +143,18 @@ class SqlWriter:
         )
         return cur.fetchone() is not None
 
+    def count_target(self, schema: str, table: str) -> int:
+        """Return ``COUNT(*)`` for ``[schema].[table]`` (compare count check)."""
+        cur = self._conn.cursor()
+        cur.execute(f"SELECT COUNT(*) FROM [{schema}].[{table}]")
+        return cur.fetchone()[0]
+
+    def read_target_ids(self, schema: str, table: str) -> list:
+        """Return every ``ID`` from ``[schema].[table]``, ascending (compare IDs)."""
+        cur = self._conn.cursor()
+        cur.execute(f"SELECT ID FROM [{schema}].[{table}] ORDER BY ID")
+        return [r[0] for r in cur.fetchall()]
+
     def _has_identity(self, schema: str, table: str) -> bool:
         """True if ``[schema].[table]`` has an IDENTITY column (the ``ID`` PK)."""
         cur = self._conn.cursor()