fix(ssr): resolve EventSource SSR violations and implement best practices

- Fix EventSource is not defined error in queue dashboard
- Add browser guards for all EventSource usage
- Replace static constants (EventSource.OPEN/CLOSED) with numeric values
- Fix setInterval SSR violation in LLM health indicator
- Replace $effect anti-pattern with onMount in share page
- Add comprehensive SvelteKit SSR best practices documentation
- Add SSR audit and testing verification

All changes follow SvelteKit best practices and are verified against
official documentation. Production build succeeds with no SSR errors.

Closes: FixEventSourceSSR
See: docs/outcomes/FixEventSourceSSR.md

dev-dist/sw.js

@@ -85,7 +85,7 @@ define(['./workbox-7a5e81cd'], (function (workbox) { 'use strict';
     "revision": "d41d8cd98f00b204e9800998ecf8427e"
   }, {
     "url": "/",
-    "revision": "0.iqtp64ssun"
+    "revision": "0.epunic0uivk"
   }], {});
   workbox.cleanupOutdatedCaches();
   workbox.registerRoute(new workbox.NavigationRoute(workbox.createHandlerBoundToURL("/"), {