Daily Temperature Wait Counter

You are given an array `readings` of daily temperature readings. For each day, determine how many days you have to wait until a warmer temperature occurs. If no future day has a warmer temperature, the answer for that day is `0`.

Return an array `result` where `result[i]` is the number of days after day `i` until a warmer reading is recorded.

**Example 1:**
```
Input: readings = [62, 58, 65, 70, 60, 72, 68, 75]
Output: [2, 1, 1, 2, 1, 2, 1, 0]
```

**Example 2:**
```
Input: readings = [90, 85, 80, 75]
Output: [0, 0, 0, 0]
```