fix: suppress svelte chunk circular dep warnings via manualChunks

Rollup was splitting svelte/src/internal/client/runtime.js into a
different chunk from svelte/src/index-client.js, producing ~35 warnings
about untrack/tick re-exports leading to broken execution order.

Add manualChunks function to vite.config.ts to colocate all svelte
node_modules into a single 'svelte-vendor' chunk, keeping runtime.js
and index-client.js together.

vite.config.ts

@@ -6,5 +6,18 @@ export default defineConfig({
     plugins: [
         tailwindcss(),
         sveltekit() // <-- Must come after Tailwind
-    ]
+    ],
+    build: {
+        rollupOptions: {
+            output: {
+                // Keep all svelte internals in one chunk to prevent circular
+                // dependency warnings between runtime.js and index-client.js
+                manualChunks(id) {
+                    if (id.includes('/node_modules/svelte/')) {
+                        return 'svelte-vendor';
+                    }
+                }
+            }
+        }
+    }
 });