A 32-year-old man from Mumbai presents with his sister, who reports that for the past 5 days he has been unusually cheerful, more energetic than normal, and has started multiple new hobbies (learning guitar, painting, and coding simultaneously). He requires only 5 hours of sleep but feels completely rested. He is more talkative and witty than usual, and his sister notes he is 'unusually confident.' He denies any history of depressive episodes. He has never required psychiatric hospitalization. Mental status examination shows elevated mood, increased psychomotor activity, and goal-directed behavior. There are no signs of psychosis. What is the most likely diagnosis?