Function scheme_value_argument 

pub fn scheme_value_argument(
    attacker: &str,
    defender: &str,
    value_at_stake: &str,
    attacker_conviction: f64,
    defender_conviction: f64,
    defender_openness: f64,
    registry: &CatalogRegistry,
) -> ValueArgumentResult

Resolve a value argument using the “Argument from Values” Walton scheme.

Builds an ASPIC+ structured system where:

• The attacker instantiates the scheme with action = "uphold_<value>", value = value_at_stake, and agent = attacker.
• The defender’s counter-argument is added as a contrary to the attacker’s conclusion.
• Preference ordering is determined by conviction levels (higher conviction wins the preference ordering).

If the scheme is absent from registry or if extension semantics yield an undecided result, the function falls back to the simple conviction-gap formula: the character with the higher conviction wins; ties favour the attacker.

Returns

A [ValueArgumentResult] containing the winner, loser, the value at stake, how much the loser’s value shifts, and the winner’s small self-reinforcement.