Count Enclosed Islands in a Grid

You are given an `m x n` grid representing land and water after flooding. - `0` represents land. - `1` represents water. - Two land cells belong to the same island if they are connected vertically or horizontally (4-directional adjacency). Return the number of **enclosed islands**: connected components of land (`0`s) that **do not touch the boundary** of the grid. Any island that touches the outer border of the grid is **not** counted. Example: - If a land region is fully surrounded by water, it counts. - If any cell in that region lies on the first/last row or first/last column, it does not count. Discuss an algorithmic approach, its time and space complexity, and how you would implement it using DFS or BFS.