Fix visual parity Lit harness broken after merge

The Lit harness stopped rendering after the merge because:

1. @a2ui/markdown-it was pinned to ^0.0.1 (npm registry) which has a
   synchronous renderMarkdown(). After commit b904548 made
   MarkdownRenderer async, the Lit directive calls .then() on the
   result, causing "markdownRenderer(...).then is not a function".

   Fix: switch to file:../../markdown/markdown-it to stay in sync with
   the local source (now async, v0.0.2).

2. The React Vite dev server lazily discovers @a2ui/web_core subpath
   imports, triggering "optimized dependencies changed. reloading"
   mid-page-load which causes blank screenshots in Playwright.

   Fix: add web_core subpath imports to optimizeDeps.include so Vite
   pre-bundles them upfront.

Author: lukasmoschitz

renderers/react/visual-parity/package-lock.json

@@ -16,7 +16,7 @@
   },
   "dependencies": {
     "@a2ui/lit": "file:../../lit",
-    "@a2ui/markdown-it": "^0.0.1",
+    "@a2ui/markdown-it": "file:../../markdown/markdown-it",
     "@a2ui/react": "file:..",
     "@lit/context": "^1.1.0",
     "lit": "^3.1.0",

renderers/react/visual-parity/package.json

@@ -28,6 +28,12 @@ export default defineConfig({
   optimizeDeps: {
     // Always re-optimize on startup so rebuilds of file: deps don't cause 504s
     force: true,
+    // Pre-bundle web_core subpath imports so Vite doesn't discover them lazily
+    // (which causes "optimized dependencies changed. reloading" mid-page-load)
+    include: [
+      '@a2ui/web_core/styles/index',
+      '@a2ui/web_core/data/model-processor',
+    ],
     exclude: [
       '@a2ui/react',
       '@a2ui/lit',