THE NATION’S FIRST cabinet-level state climate chief learned to shoot a shotgun before she could drive, started her career working as a public high school teacher in San Francisco, and raises goats on her nearly 18-acre property smack dab in the middle of Massachusetts — and has the homemade yogurt to prove it. Melissa Hoffer is the force behind Gov. Maura Healey’s climate agenda, or what’s left of it, anyway.