Pure refactor. No behavior change. Introduces a TokenSource trait so
additional backends (AWS Secrets Manager, Vault, etc.) can plug in
behind feature flags without touching the server wiring.
- New module crates/omnigraph-server/src/auth.rs with the TokenSource
trait and a single EnvOrFileTokenSource implementation that delegates
to the existing server_bearer_tokens_from_env() function.
- serve() now constructs EnvOrFileTokenSource and calls load() instead
of calling the free function directly.
- The trait has a supports_refresh() hook (false for env/file) for
future implementations that can rotate without restart.
- async-trait added to omnigraph-server deps; it's already in the
workspace.
Tests:
- Unit tests in auth.rs covering load paths and the default supports_refresh
/ name values.
- Existing 128 tests (lib + integration + openapi) pass unchanged.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
