```ts
/**
 * Merges overlapping intervals into the smallest list of non-overlapping pairs.
 * @param intervals - List of [start, end] pairs to merge.
 * @returns A new list of merged [start, end] pairs, sorted ascending by start.
 */
export function mergeIntervals(intervals: number[][]): number[][] {
    if (intervals.length === 0) return [];

    const sortedIntervals = intervals.slice().sort((a, b) => a[0] - b[0]);
    const merged: number[][] = [sortedIntervals[0]];

    for (let i = 1; i < sortedIntervals.length; i++) {
        const current = sortedIntervals[i];
        const lastMerged = merged[merged.length - 1];

        if (current[0] > lastMerged[1]) {
            merged.push(current);
        } else if (current[1] > lastMerged[1]) {
            merged[merged.length - 1] = [lastMerged[0], current[1]];
        }
    }

    return merged;
}
```