[codex] Refactor binary tree right side view

[eselyavka]

Summary

Refactor LeetCode 00199 to keep a single BFS solution for binary tree right side view.

Details

• Replace list-based queue operations with collections.deque.
• Remove the duplicate Solution2 implementation that did the same level-order traversal work.
• Return [] for an empty tree and cover that case in the unit test.

Validation

• python3 practice/leetcode/solutions_00000/solution_00199.py
• Commit hook: pytest (805 passed) and pylint on changed Python files (10.00/10)