Function parse_query_string 

pub fn parse_query_string(query: &str, config: &QueryConfig) -> QueryParams

Parse query parameters from a URL query string.

Reads:

• page — 1-based page number (default 1, min 1).
• page_size / pageSize / per_page — items per page (default from config, clamped to 1..=max_page_size).
• sort — column to sort by (must be in allowed_sorts when non-empty).
• order — asc or desc (default asc).
• All other keys are treated as filters (must be in allowed_filters when non-empty).