chore: add Chromium installation for Karma tests and update devcontainer configuration

.devcontainer/Dockerfile

@@ -8,6 +8,11 @@ ARG PNPM_VERSION=11.5.0
 ENV PNPM_HOME=/home/node/.local/share/pnpm
 ENV PATH=${PNPM_HOME}:${PATH}
 
+# Install Chromium for Karma/ChromeHeadless test execution inside the container.
+RUN apt-get update \
+    && apt-get install -y --no-install-recommends chromium \
+    && rm -rf /var/lib/apt/lists/*
+
 # Configure Corepack-managed pnpm globally at image build time.
 RUN corepack enable \
     && corepack prepare pnpm@${PNPM_VERSION} --activate \

.devcontainer/devcontainer.json

@@ -47,7 +47,8 @@
     "CI": "true",
     "NODE_ENV": "development",
     "NO_UPDATE_NOTIFIER": "1",
-    "PNPM_STORE_DIR": "/home/node/.pnpm-store"
+    "PNPM_STORE_DIR": "/home/node/.pnpm-store",
+    "CHROME_BIN": "/usr/bin/chromium"
   },
 
   "mounts": ["source=alfresco-ng2-pnpm-store,target=/home/node/.pnpm-store,type=volume"],