docs: consolidate passkey docs and add embedded enrollment guide

[tomauth0]

• Merge native-passkeys-api.mdx and native-passkeys-for-mobile-applications.mdx into passkey-apis.mdx ("Passkey APIs for Embedded Applications"). Cover iOS, Android, and web with platform-specific tabs for client-side credential APIs; defer parameter reference to the My Account API explorer instead of duplicating tables.

• Correct app-association guidance: Auth0 hosts apple-app-site-association and assetlinks.json automatically based on Device Settings; developers do not host these files themselves.

• Rewrite cross-platform guidance: synced credentials handle the common case (no QR code needed); hybrid transport is a fallback for cross-ecosystem or shared-device scenarios only. Avoid setting rpId at the eTLD+1; prefer a parent subdomain scoped to auth surfaces.

• Add new Embedded Login Enrollment use case (authenticate/login/embedded-login/use-cases/enrollment.mdx) covering MFA factor enrollment, passkey enrollment, connected accounts, and self-service authentication method management.

• Update embedded-login.mdx capabilities to mention native social login and broaden passkey support to web + iOS + Android.

• Remove Early Access warnings from Passkey APIs and My Account API pages now that they are GA.

• Add redirects from old passkey URLs to the consolidated page; update inbound links in passkeys.mdx, passwordless.mdx, my-account-api.mdx, and api/myaccount.mdx.

Description

References

Testing

Checklist

• I've read and followed CONTRIBUTING.md.
• I've tested the site build for this change locally.
• I've made appropriate docs updates for any code or config changes.
• I've coordinated with the Product Docs and/or Docs Management team about non-trivial changes.

[hazel-nut]

looks like you have some merge conflicts and unverified commits you'll need to fix, and you'll need to add redirects for the pages you're deleting. 🙂 happy to review more fully for content afterwards!