Update README with LeetCode Daily Challenge

Author: jeremymanning

README.md

@@ -25,6 +25,7 @@ This means you'll always find an AI-generated solution to compare with or learn
 | April 3, 2026 | [3661](https://leetcode.com/problems/maximum-walls-destroyed-by-robots/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/3661) | 🔴 Hard |
 | April 4, 2026 | [2075](https://leetcode.com/problems/decode-the-slanted-ciphertext/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/2075) | 🟡 Medium |
 | April 5, 2026 | [657](https://leetcode.com/problems/robot-return-to-origin/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/657) | 🟢 Easy |
+| April 6, 2026 | [874](https://leetcode.com/problems/walking-robot-simulation/description/?envType=daily-question) | [Click here](https://github.com/ContextLab/leetcode-solutions/tree/main/problems/874) | 🟡 Medium |
 
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