After the auth-axis migration, the OpenCode bridge consults this enum
solely to decide whether to read `provider.key` and stamp it on
`model.apiKey`. The bearer / anthropic-api-key / google-api-key
distinctions used to control which header the bridge wrote; that is now
the adapter's Auth axis's job.
Three of four variants were write-only after the migration. Collapse to:
- 'key' — provider needs an API key
- 'none' — provider does not (e.g. local)
Updated all six provider resolvers and the resolver test fixtures.
Kit Langton
8b414cdb5a