Fix CI: build renderer dependencies before composer

- Add web_core and react renderer build steps before composer install
- Add renderer paths to CI trigger so composer rebuilds when
  renderers change (local file dependency)

Author: lukasmoschitz

.github/workflows/composer_build_and_test.yml

@@ -18,10 +18,14 @@ on:
   push:
     paths:
       - 'tools/composer/**'
+      - 'renderers/react/**'
+      - 'renderers/web_core/**'
       - '.github/workflows/composer_build_and_test.yml'
   pull_request:
     paths:
       - 'tools/composer/**'
+      - 'renderers/react/**'
+      - 'renderers/web_core/**'
       - '.github/workflows/composer_build_and_test.yml'
 
 jobs:
@@ -43,6 +47,14 @@ jobs:
           cache: 'pnpm'
           cache-dependency-path: 'tools/composer/pnpm-lock.yaml'
 
+      - name: Build web_core (dependency of @a2ui/react)
+        working-directory: ./renderers/web_core
+        run: npm ci && npm run build
+
+      - name: Build React renderer (local file dependency)
+        working-directory: ./renderers/react
+        run: npm ci && npm run build
+
       - name: Install dependencies
         working-directory: ./tools/composer
         run: pnpm install