Count same-color squares in a character grid

You are given a 2D grid (matrix) of characters. Each character represents a color: cells with the same character are considered the same color. Formally: - The grid has `m` rows and `n` columns. - `grid[i][j]` is an alphabetic character (e.g., `'a'`–`'z'` or `'A'`–`'Z'`). A **square** in this grid is defined as a contiguous `k × k` submatrix aligned with the grid axes, for some integer `k ≥ 1`. A square is **monochromatic** if **all** of its cells contain the **same** character (i.e., the same color). Task: - Count and return the total number of monochromatic squares in the grid. - Count all sizes of squares (1×1, 2×2, ..., up to the largest possible that fits in the grid). Example (just for clarity, not necessarily exhaustive): If the grid is: ``` a a b a a b b b b ``` Then some monochromatic squares include: - All 1×1 cells (each single cell is a monochromatic square). - The 2×2 square in the top-left corner formed by `'a'`. Your function should return the total count of such monochromatic squares for a given input grid.