Update README with LeetCode Daily Challenge

Author: jeremymanning

README.md

@@ -39,6 +39,7 @@ This means you'll always find an AI-generated solution to compare with or learn
 | December 17, 2025 | [3573](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-v/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/3573) | 🟡 Medium |
 | December 18, 2025 | [3652](https://leetcode.com/problems/best-time-to-buy-and-sell-stock-using-strategy/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/3652) | 🟡 Medium |
 | December 19, 2025 | [2092](https://leetcode.com/problems/find-all-people-with-secret/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2092) | 🔴 Hard |
+| December 20, 2025 | [944](https://leetcode.com/problems/delete-columns-to-make-sorted/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/944) | 🟢 Easy |
 
 </details>