```python
from typing import List, Dict

def column_digest(rows: List[List[int]], column: int) -> Dict[str, float]:
    if column < 0:
        raise ValueError("Column index must be non-negative")
    
    count = 0
    min_val = None
    max_val = None
    total_sum = 0
    
    for row in rows:
        if len(row) > column:
            count += 1
            cell_value = row[column]
            total_sum += cell_value
            
            if min_val is None or cell_value < min_val:
                min_val = cell_value
            if max_val is None or cell_value > max_val:
                max_val = cell_value
    
    if count == 0:
        return {
            "count": 0,
            "min": 0,
            "max": 0,
            "mean": 0,
            "median": 0
        }
    
    mean = total_sum / count
    median = sorted(row[column] for row in rows)[count // 2]
    
    return {
        "count": count,
        "min": min_val,
        "max": max_val,
        "mean": round(mean, 2),
        "median": round(median, 2)
    }
```