docs(docs): add Approach and Explanation sections with mermaid diagrams to problem pages

apps/docs/content/(array)/875-koko-eating-bananas.mdx

@@ -26,6 +26,22 @@ sidebar:
 - `piles.length <= h <= 10^9`
 - `1 <= piles[i] <= 10^9`
 
+## Approach
+
+```mermaid
+flowchart TD
+  S(["minEatingSpeed(piles, h)"]) --> I["l = 1, r = max(piles)"]
+  I --> W{"l < r?"}
+  W -- no --> E(["return l — the smallest workable speed"])
+  W -- yes --> M["mid = floor((l + r) / 2)"]
+  M --> K["kWorks(mid): hours = sum of ceil(p / mid)"]
+  K --> Q{"hours <= h?"}
+  Q -- yes --> A["r = mid — keep mid, try slower"]
+  Q -- no --> B["l = mid + 1 — too slow, speed up"]
+  A --> W
+  B --> W
+```
+
 ## Solution
 
 ```js
@@ -60,3 +76,7 @@ var minEatingSpeed = function(piles, h) {
   return l;
 };
 ```
+
+## Explanation
+
+<YouTube id="U2SozAs9RzA" title="Koko Eating Bananas - Binary Search - Leetcode 875 - Python" />