feat: db constistancy

src/usecase/placement/fetch_placement_post_cycle.py

@@ -37,6 +37,17 @@ async def fetch_placement_post_cycle(self: 'Usecase', interval_seconds: int) ->
             ).first()
 
             if matching_post:
+                # Validate channel consistency
+                if matching_post.channel_id != placement.placement_channel_id:
+                    log.error(
+                        'Post %s channel_id mismatch: expected %s, got %s. Skipping placement %s',
+                        matching_post.id,
+                        placement.placement_channel_id,
+                        matching_post.channel_id,
+                        placement.id,
+                    )
+                    continue
+
                 placement.post = matching_post
                 await placement.save()
                 updated_count += 1