Rotate Image

You are given an `n x n` 2D `matrix` representing an image. Rotate the image by **90 degrees clockwise**. You have to rotate the image **in-place**, which means you have to modify the input 2D matrix directly. Return the modified matrix. **Hint:** First transpose the matrix (swap `matrix[i][j]` with `matrix[j][i]`), then reverse each row. **Example 1:** Input: matrix = [[1,2,3],[4,5,6],[7,8,9]] Output: [[7, 4, 1], [8, 5, 2], [9, 6, 3]] **Example 2:** Input: matrix = [[5,1,9,11],[2,4,8,10],[13,3,6,7],[15,14,12,16]] Output: [[15, 13, 2, 5], [14, 3, 4, 1], [12, 6, 8, 9], [16, 7, 10, 11]] **Example 3:** Input: matrix = [[1]] Output: [[1]]