Get Founder Slots

Returns remaining founder cohort slots — public endpoint, no auth required. Used by the pricing page to display the scarcity counter. Returns {remaining: int, max: int, active: bool}. active=false when the founder price ID is not configured (feature disabled).

The displayed count MUST be the true used_slots value. A prior revision inflated it with a +63 display baseline; a fabricated "claimed" count is false scarcity (FTC deceptive-practice exposure) and is not permitted on any purchase surface.