Token bucket with fractional refill

Implement a token-bucket rate limiter. The bucket holds at most `capacity` tokens and refills at `refill_rate` tokens per second (fractional accrual allowed). It starts full at capacity. Process a list of request events as [timestamp, cost] pairs with non-decreasing integer timestamps. Before each request, add (timestamp - last_timestamp) * refill_rate tokens, clamped at capacity. If the bucket holds at least `cost` tokens, allow the request and subtract `cost`; otherwise deny it and leave the bucket unchanged. The first event uses the bucket's initial full state with no prior refill. Return a list of booleans: True if allowed, False if denied. capacity and refill_rate are positive numbers.