fix: rebuild dependent modules when new module detected (#2929)

Fixes #2899

![Screenshot 2024-10-01 at 12 33
12 PM](https://github.com/user-attachments/assets/1b8caaae-47c1-478d-86d2-9280dfbf10f8)

internal/buildengine/engine.go

@@ -531,7 +531,7 @@ func (e *Engine) watchForModuleChanges(ctx context.Context, period time.Duration
 			}
 			existingHash, ok := moduleHashes[change.Name]
 			if !ok {
-				continue
+				existingHash = []byte{}
 			}
 
 			hash, err := computeModuleHash(change.Module)