fix(http): honor [RoutePrefix] when no global prefix is configured

[outofrange-consulting]

Fixes #2705.

RoutePrefixPolicy.Apply had an early-exit that skipped iterating chains whenever there was no GlobalRoutePrefix and no NamespacePrefixes. That short-circuit also bypassed the per-handler [RoutePrefix] attribute, so a class-level prefix declared on its own was silently dropped.

You normally wouldn't notice — the route just ended up missing one segment. API Versioning made it obvious because the version-segment policy still ran and produced things like /v1/create instead of /v1/items/create for:

[RoutePrefix("items")]
public static class TodoCreationEndpoint
{
    [WolverinePost("/create")]
    public static void Post() { }
}

The fix is just to drop the early-exit. DeterminePrefix already returns null when nothing applies, so the loop is a no-op for chains without any prefix.

Tests

• apply_honors_attribute_prefix_when_no_global_or_namespace_prefix_configured — unit test for the Apply path that wasn't covered before (existing tests only exercised DeterminePrefix in isolation, which never tripped the bug).
• gh_2705_attribute_prefix_combines_with_api_versioning — exact reproduction from the issue: [RoutePrefix("items")] + [WolverinePost("/create")] + versioning with DefaultVersion = ApiVersion(1) and UnversionedPolicy.AssignDefault. Asserts the final route is /v1/items/create.

Verified red → green by stashing the fix (test fails with /v1/create) and restoring it.

[jeremydmiller]

@outofrange-consulting Thank you!