CASE 1: Daniel, a 58-year-old man, has type 2 diabetes treated with metformin and gliclazide (latest HbA1c 8.4%). He smokes 15 cigarettes a day and has for 35 years. He has 26 teeth, none lost to periodontitis. Probing depths are generally 5-7 mm with bleeding on probing, the worst radiographic bone loss (about 45% of root length) is at tooth 36, which has a Class II furcation. Using the 2017 classification, which diagnosis best fits Daniel's periodontal condition?