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

vite.config.ts

@@ -19,10 +19,16 @@ export default defineConfig({
         SvelteKitPWA({
             srcDir: './src',
             mode: 'development',
-            strategies: 'generateSW',
+            strategies: 'injectManifest',
+            filename: 'service-worker.ts',
             scope: '/',
             base: '/',
             selfDestroying: process.env.SELF_DESTROYING_SW === 'true',
+            injectManifest: {
+                swSrc: 'src/service-worker.ts',
+                swDest: 'service-worker.js',
+                injectionPoint: 'self.__WB_MANIFEST'
+            },
             manifest: {
                 short_name: 'InstaChef',
                 name: 'InstaChef Recipe Saver',