Peak simultaneous bookings

Question

Given a list of half-open time ranges, report the largest number of ranges that are active at the same instant.

```python
def solve(raw: str) -> str: ...
```

## Requirements

- Line 1 holds the number of bookings. Each following line holds `start end`, two integers with `start` strictly less than `end`.
- Treat a booking as occupying the half-open interval `[start, end)`.
- Because the interval is half-open, a booking that ends at a time does not conflict with one that starts at that same time.
- Return the peak number of concurrent bookings as a decimal string.
- An empty booking list returns `"0"`.
- `run_case(case: dict)` forwards `case["stdin"]` to `solve`.
- Do not append a trailing newline to the returned string; return the value exactly once.