Query String Parser

Summary

Add query string parsing utilities for key-value extraction.

Requirements

• Parse query string into key-value pairs
• Handle URL-encoded values
• Handle multiple values for same key
• Handle array notation (key[]=value)
• Iterator interface for memory efficiency

Example API

const uri_result = try uri.parse("http://example.com?a=1&b=2&c=3");
var iter = uri.queryIterator(uri_result.query.?);
while (iter.next()) |param| {
    // param.key, param.value
}

Acceptance Criteria

• Correct parsing of standard query strings
• Handles edge cases (empty values, special chars)
• Tests for various query formats