Take reference for Real::min/Real::max

[TimTheBig]

This may save a clone in many cases

[gemini-code-assist]

Code Review

This pull request updates the min and max methods of the Real struct in src/real/arithmetic.rs to accept and return references with a lifetime parameter instead of taking ownership of the values. There are no review comments, so I have no feedback to provide.

[timschmidt]

1. High: Rational parsing now accepts zero denominators and leaves fractions unreduced.
   In hyperreal/src/rational/arithmetic.rs:1611, the fraction parser constructs Self directly instead of checking denominator.is_zero() and
   calling from_fraction_parts(...).reduce(). Confirmed failure: "1/0".parse::() returns Ok(Rational { denominator: 0 }), and "9/18"
   no longer canonicalizes to 1/2.
2. High: Derived Deserialize bypasses Rational invariants.
   hyperreal/src/rational/arithmetic.rs:52 replaces the custom deserializer with Deserialize, so JSON can create invalid or noncanonical
   rationals, including denominator zero. Confirmed with {"sign":1,"numerator":[1],"denominator":[]} deserializing successfully instead of
   erroring.
3. High: CBOR rational pairs with denominator zero now panic instead of returning Problem::DivideByZero.
   In hyperreal/src/serde.rs:73, the code divides Rational::from_bigint(numerator) / Rational::from_bigint(denominator). When denominator is
   zero, this reaches an internal assertion in rational division. The previous implementation used from_bigint_fraction, which returned a
   proper error.
4. Medium: Simple::from_str accepts trailing input.
   hyperreal/src/simple.rs:682 now returns after parsing the first expression without checking remaining characters. Confirmed: (+ 1 2) junk is
   accepted and evaluates to 3.

[timschmidt]

I fixed up the issues, at least well enough that tests pass, and there was a performance improvement, so I pulled it in.

[TimTheBig]

thanks