There was the Ikea store in Ballymun and a wind farm in Leitrim. Now the Ingka Group, the main retail arm of the Ikea global furniture business, has decided to invest €100 million in social housing in Dublin.  The full details of the sites, the funding format and the local authorities that would ultimately own the homes have yet to be confirmed. But if it works, the model could be replicated elsewhere, the firm’s investment managers have told The Currency. And, as we revealed last month, Ingka is sitting on €30 billion in accumulated profits managed out of Dublin –…