Add a specification/v2_auth.md landing page summarizing the four auth specs
(EMA / XAA, Hardening, Mid-session, Smoke testing) with a section submenu,
mirroring the V2 UX index pattern.
Add a V2 Auth link (after V2 UX) and a V2 New Spec Impact link to every spec
page's top menu so the top-level nav is uniform, and restructure the four
v2_auth_*.md pages onto the shared two-tier menu (top menu + auth submenu).
Docs only.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01S3fTN8H3R8YV4yUGvZjYnX
