Replaced slow $effect-based auth checks with synchronous IIFE scripts in <svelte:head> that run during HTML parsing, before Svelte hydration. Covers: /today, /admin, /admin/schedule, /manage, /notifications (admin-only), and /account (auth-required). All redirect via window.location.replace() with no page flash.
Ultraworked with [Sisyphus](https://github.com/code-yeongyu/oh-my-openagent)
Co-authored-by: Sisyphus <clio-agent@sisyphuslabs.ai>