Count connected land components in a grid

You are given a 2D grid of characters where: - `'1'` represents land - `'0'` represents water A group of land cells forms an **island** if they are connected **4-directionally** (up, down, left, right). Determine the number of islands in the grid. ## Input - `grid`: an `m x n` matrix of characters (`'0'` or `'1'`). ## Output - Return an integer: the number of islands. ## Constraints - `1 <= m, n <= 300` - `grid[i][j] ∈ {'0','1'}` ## Notes - Diagonal adjacency does **not** connect islands. - You may modify the grid in-place if desired.