Recently-used model is picked even when config excludes its provider

Description

If you have used a model from one provider and later change your config to declare only a different provider, opencode keeps starting sessions on the old model. I hit this moving from Anthropic to a local OpenAI-compatible endpoint: my config lists only the local provider, but new sessions still came up on claude-sonnet-4-5.

In defaultModel (packages/opencode/src/provider/provider.ts) the recently-used list is walked before Object.keys(cfg.provider) is computed, and the loop never consults it. The configured-provider allowlist only gates the fallback path below the loop, so anything in the recent list wins regardless of what the config says.

OpenCode version

1.18.7 (reproduced on dev @ 55b0211690)

Steps to reproduce

1. Use a model from provider A at least once so it lands in the recent-models list (model.json in opencode's state dir).
2. Change your config so provider contains only provider B.
3. Start a new session without -m.

Expected: a model from provider B. Actual: the provider A model from step 1.

Operating System

macOS 26.5.2