examples: provider auth in SSR and SPA for Auth0, Apple, Microsoft and Google #32

Goal

Runnable examples proving provider auth "just works" in both SSR and SPA modes for Auth0, Apple, Microsoft and Google, built on askr-server provider sign-in (askrjs/askr-server#76) and the askr router binding (askrjs/askr#777). These replace the browser-session examples being removed from askr-auth (askrjs/askr-auth#65).

Requirements

• One example app (or one per provider, whichever is clearer) using the first-party Vite+ toolchain, runnable in SSR and SPA modes.
• Each provider shows: setup, sign-in, callback, reload restoration, protected route redirect with next, session expiry/renewal or interactive recovery, local logout (plus provider logout where supported), and error states.
• API access from server actions only: Microsoft Graph (one call), a Google API after separate consent (one call), and an Auth0 API audience (one call). Apple shows the real server exchange boundary and first-login profile handling.
• No tokens or secrets in the browser, the repo or the README. Configuration comes from environment variables, with setup instructions that match askr add auth output.
• Local HTTPS / tunnel instructions, including Apple's no-localhost constraint.
• A simulated-provider mode so CI can run every example without live credentials.

Acceptance criteria

• CI runs each example against simulated providers in Chromium, Firefox and WebKit, in SSR and SPA modes.
• Examples are the source used for live qualification (qualify: live provider qualification for Auth0, Apple, Microsoft and Google askr-auth#71).

Depends on askrjs/askr-server#76 and askrjs/askr#777 and the provider presets. Part of askrjs/askr-auth#64.