EqualifyEverything / equalify-reflow

The login page previously showed only "Sign in"; the brand reads discontinuous between login and the post-login viewer. Add the same "Equalify Reflow" wordmark + Beta pill that PipelineViewerPage uses, gated on the existing VITE_SHOW_UIC_LOGO flag for the optional logo. After login, a logged-in user had no way to sign out. Add a UserMenu component slotted into the right side of PipelineViewerPage's header: "Signed in as <name>" + a Sign out button that POSTs to /api/v1/auth/logout (apiFetch handles X-CSRF-Token) and bounces to /login. Renders nothing when AUTH_MODE=none — zero behaviour change under the OSS default. Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>