Add IGlobalOptionsAccessor for typed access to global options

[carldebilly]

Summary

• IGlobalOptionsAccessor is now registered in DI automatically, giving middleware, DI service factories, and handlers typed access to parsed global option values.
• UseGlobalOptions<T>() extension on ReplApp allows declaring a typed class whose public settable properties become global options — the class is available via DI, populated from parsed values. Property names are converted to kebab-case (MaxRetries → --max-retries).
• New non-generic AddGlobalOption(name, typeName) overload accepts constraint-style type names ("int", "bool", "guid", "uri", "date", "timespan", etc.), matching the route constraint naming convention.
• GlobalOptionDefinition now preserves the declared Type from AddGlobalOption<T>() for help text generation and future validation.
• Values are updated per-invocation: in CLI mode after initial parsing, in interactive mode after each command's re-parse. DI singleton factories see the correct values because they resolve lazily (after parsing completes).

Examples

Dictionary-style access (works with both CoreReplApp and ReplApp):

app.Options(o => o.Parsing.AddGlobalOption<string>("tenant"));

// In middleware
app.Use(async (ctx, next) =>
{
    var globals = ctx.Services.GetRequiredService<IGlobalOptionsAccessor>();
    var tenant = globals.GetValue<string>("tenant");
    await next();
});

// In DI factory
services.AddSingleton<ITenantClient>(sp =>
{
    var globals = sp.GetRequiredService<IGlobalOptionsAccessor>();
    return new TenantClient(globals.GetValue<string>("tenant", "default")!);
});

Typed class (requires ReplApp with MS DI):

public class MyGlobalOptions
{
    public string? Tenant { get; set; }
    public int Port { get; set; } = 8080;
}

app.UseGlobalOptions<MyGlobalOptions>();
app.Map("show", (MyGlobalOptions opts) => $"{opts.Tenant}:{opts.Port}");

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