fix: preserve fragments in curl GET query parsing

[ryanfowler]

Summary

• Insert --from-curl -G query data before URL fragments
• Preserve existing query strings when appending curl GET data
• Reject negative --from-curl numeric values consistently

Validation

• cargo fmt
• cargo test --locked --all-features --lib from_curl -- --nocapture
• cargo test --locked --all-features --lib test_parse_rejects_negative_numeric_values -- --nocapture