The global provider bootstrap froze all three ModelRuntime mutation
methods after startup, so a provider extension that fetched an updated
model catalog had that work silently discarded.
registerProvider is now applied when the provider ID is already in the
frozen baseline and the incoming config equals the recorded baseline in
every field except `models`. Refreshing extensions re-send a complete
provider config rather than a models-only delta, so the test is
"equal except models", not "contains only models".
Everything else stays a logged no-op: unknown provider IDs, any change
to name/baseUrl/apiKey/api/streamSimple/headers/authHeader/oauth/
refreshModels, native registration, and unregistration. Function-valued
fields compare by reference and so always read as a mismatch, which is
the intended conservative direction.
An accepted update rebases the stored baseline from Pi's merged record,
so repeat refreshes work and an unchanged replay is correctly ignored
rather than re-applied on every session start. The accept path stays
synchronous and never awaits or networks; Pi's own trailing
fire-and-forget local refresh is untouched.
