Find Maximum Envelope Nesting

You are given a list of envelopes, where each envelope is represented by `[width, height]`. One envelope can be placed inside another only if both its width and height are strictly smaller than the other envelope's. Envelopes cannot be rotated. Return the maximum number of envelopes that can be nested. Example: - Input: `[[5,4],[6,4],[6,7],[2,3]]` - Output: `3` - Explanation: One valid nesting chain is `[2,3] -> [5,4] -> [6,7]`. Assume the input size can be large enough that an efficient solution is required.