docs: fix stale "static resolution" fallback comments

ResolveDataAPIToken is discovery-only since 10aa97eec: a host that doesn't advertise /.well-known/entire-api.json is a surfaced error, not a fall-through to static resolution. Three comments still described the removed fallback — recap.go and dispatch/mode_local.go on the call side, and api_discovery.go's ErrDiscoveryUnavailable doc on the source side (which invited a future caller to reintroduce the fallback). The no-fallback docs-alignment pass (087f5a498) missed these.