dsa-solutions

Add a finished DSA solution to this repo from a problem link plus the solution code. Use this whenever the user wants to file, save, commit, or "add" a LeetCode / Codeforces / CF-EDU solution they've already written — even if they just paste a URL and a code block without saying the word "skill". Handles scaffolding via ./scripts/new and fills in the metadata header (complexity, notes, tags) in the user's established style.