fix: async row_reader in _ingest_schemas + X2BEE DB validation

Fixed coroutine handling: row_reader returns coroutine for async DBs
(PostgreSQL), needs await. Used asyncio.iscoroutine() check.

Validated on real X2BEE production DB (AWS RDS PostgreSQL):
  ai_lab_main: 6 tables, 19,843 rows → 19,843 nodes in 36.7s
  - pr_goods_base: 1,008 products
  - pr_goods_sold_hist: 3,370 sales (FK → products)
  - pr_goods_user_feedback: 15,374 reviews (FK → products)
  Batch processing: 15K feedback rows split into 10K + 5K batches
  Search: "Wine Niagara" → instant hit ✅

Author: SonAIengine

src/synaptic/extensions/db_ingester.py

@@ -695,7 +695,8 @@ async def _ingest_schemas(
         has_fk = [s for s in regular if s.foreign_keys]
 
         for schema in no_fk + has_fk:
-            rows = await row_reader(schema.name) if asyncio.iscoroutinefunction(row_reader) else row_reader(schema.name)
+            result = row_reader(schema.name)
+            rows = await result if asyncio.iscoroutine(result) else result
             if not rows:
                 continue
 
@@ -721,7 +722,8 @@ async def _ingest_schemas(
 
         # M:N join tables → direct edges (no intermediate nodes)
         for schema in join_tables:
-            rows = await row_reader(schema.name) if asyncio.iscoroutinefunction(row_reader) else row_reader(schema.name)
+            result = row_reader(schema.name)
+            rows = await result if asyncio.iscoroutine(result) else result
             if not rows:
                 continue