Move AuthService off the removed AuthStorage / ModelRegistry.create surface
onto the async ModelRuntime API:
- AuthService.create({ agentDir | runtime }) async factory wrapping
ModelRuntime.create({ authPath, modelsPath }); createModelRuntimeForAgentDir
replaces createModelRegistryForAgentDir.
- saveApiKey -> runtime.login(providerId, "api_key", nonInteractive) so the
key is persisted through the runtime credential store.
- logoutProvider -> runtime.logout; refreshAuthState -> await runtime.refresh().
- startOAuthLogin now passes the runtime into OAuthLoginFlowService.start.
- authProviders/requireOAuthLoginProvider became async around getLogin/Logout
provider options.
- sessiond.ts: async createRuntime, AuthService.create, pass modelRuntime to
PiSessionService; sessionDaemonStartup awaits createRuntime.
Cross-slice: authProviderOptions (2), oauthLoginFlowService (3), and
piSessionService (4) still expose the old ModelRegistry shape, so the tree does
not fully typecheck yet. Session-daemon path changed -> manual sessiond restart
needed once the migration lands.
