Enable Playwright e2e tests in dev container and CI pipeline

.devcontainer/Dockerfile

@@ -3,9 +3,22 @@
 
 FROM mcr.microsoft.com/devcontainers/javascript-node:1-22-bookworm
 
-# Install system deps if needed (none required for static site)
+# Install system deps for static site tooling + Playwright (e2e tests)
 RUN apt-get update && apt-get install -y --no-install-recommends \
     curl \
+    # Playwright browser dependencies (so e2e tests run inside devcontainer)
+    libnspr4 \
+    libnss3 \
+    libatk1.0-0 \
+    libdbus-1-3 \
+    libatspi2.0-0 \
+    libxcomposite1 \
+    libxdamage1 \
+    libxfixes3 \
+    libxrandr2 \
+    libgbm1 \
+    libxkbcommon0 \
+    libasound2 \
     && rm -rf /var/lib/apt/lists/*
 
 # Ensure workspace dir exists (mount point)