Maximize coins collected by tokens jumping +3

You are given a single-player board game represented by a string board of length N (1 ≤ N ≤ 100). Each character is one of:

• '.': empty cell
• 'T': a player token (there may be multiple tokens)
• 'C': a coin

A move consists of selecting one token and moving it exactly 3 positions to the right (from index i to i+3). The token does not interact with intermediate cells.

Rules:

• A move is only allowed if i+3 < N.
• A move is not allowed if the destination cell currently contains another token ('T').
• If a token lands on a cell containing a coin ('C'), that coin is collected and removed (each coin can be collected at most once).
• Tokens can be moved multiple times.

Task: Return the maximum number of coins that can be collected.

Function signature:

def solution(board: str) -> int:
 ...

Examples:

• board = "TT.T.CCCCC" → 3
• board = "T...CCCC" → 1
• board = "C..TT.CT.C" → 2