Add POI feature and imporve the overall backend implementation

services/pos/app/repositories/pos_config_repository.py

@@ -80,3 +80,40 @@ class POSConfigurationRepository(BaseRepository[POSConfiguration, dict, dict]):
         except Exception as e:
             logger.error("Failed to count configurations by tenant", error=str(e), tenant_id=tenant_id)
             raise
+
+    async def get_by_pos_identifier(
+        self,
+        pos_system: str,
+        identifier: str
+    ) -> Optional[POSConfiguration]:
+        """
+        Get POS configuration by POS-specific identifier
+
+        Args:
+            pos_system: POS system name (square, toast, lightspeed)
+            identifier: merchant_id, location_id, or other POS-specific ID
+
+        Returns:
+            POSConfiguration if found, None otherwise
+        """
+        try:
+            query = select(self.model).where(
+                and_(
+                    self.model.pos_system == pos_system,
+                    or_(
+                        self.model.merchant_id == identifier,
+                        self.model.location_id == identifier
+                    ),
+                    self.model.is_active == True
+                )
+            ).order_by(self.model.created_at.desc())
+
+            result = await self.session.execute(query)
+            return result.scalars().first()
+
+        except Exception as e:
+            logger.error("Failed to get config by POS identifier",
+                        error=str(e),
+                        pos_system=pos_system,
+                        identifier=identifier)
+            raise