routes/oauth.js has its own pageLocals object (distinct from
routes/index.js's values and routes/docs.js's own copy) used by
oauth_authorize.ejs/oauth_logout.ejs -- missed in the white-label
change since a grep alias in this environment silently treats this
particular file as binary and skips it. Caught by CI (oauth.test.js),
not local testing. Added logo: conf.logo to match the other two
copies of this locals object.