A 32-year-old male labourer from rural Maharashtra sustained a closed fracture of the mid-shaft femur 6 weeks ago. He was treated conservatively with skeletal traction followed by a long leg cast. On clinical examination today, there is minimal tenderness over the fracture site, and the limb shows early weight-bearing tolerance. X-rays reveal bridging callus across the fracture with partial obliteration of the fracture line. Which stage of fracture healing is most likely present?