Refresh standard OpenRouter catalog even when named profile owns slot (#292)

A named provider profile (e.g. [providers.mynvidia] for NVIDIA NIM) sets
JCODE_OPENROUTER_API_BASE when active, which made the previous guard
explicit_openrouter_runtime_configured() skip the standard OpenRouter
catalog refresh entirely. That is exactly the reporter's config, so the
prior commit would not have helped him.

The refresh always targets canonical openrouter.ai with OPENROUTER_API_KEY
and writes to the dedicated 'openrouter' cache namespace, so it is safe to
run regardless of the shared-slot runtime env. Remove the guard and add a
regression test covering the named-profile-owns-slot scenario.