chrome-service: replace static health stub with noVNC view

The static nginx stub at chrome.viktorbarzin.me wasn't useful for
debugging anti-bot interactions. Swap it for a live noVNC HTML5 view
of the headed Chromium session: x11vnc taps Xvfb's :99 over localhost
TCP (added `-listen tcp -ac` to Xvfb), websockify wraps it as a WS
endpoint, and noVNC's vendored web client serves it on :6080.

The ingress chain is unchanged — chrome.viktorbarzin.me stays
Authentik-gated, dns_type=proxied, port 3000 (the Playwright WS) stays
internal-only behind the NetworkPolicy + token. Custom image
`registry.viktorbarzin.me/chrome-service-novnc:v4` (ubuntu:24.04 +
x11vnc + websockify + novnc apt packages) needs imagePullSecrets, so
also added registry-credentials reference to the deployment spec.

x11vnc flags: `-noshm -noxdamage -nopw -shared -forever`. SHM is
disabled because each container has its own /dev/shm so the X server
can't grant access; XDAMAGE isn't compiled into the noble Xvfb. The
sidecar entrypoint waits up to 30s for both Xvfb (:6099) and x11vnc
(:5900) to bind before exec'ing websockify.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

stacks/chrome-service/files/novnc/Dockerfile

@@ -0,0 +1,19 @@
+FROM docker.io/library/ubuntu:24.04
+
+RUN apt-get update \
+ && apt-get install -y --no-install-recommends \
+      x11vnc \
+      novnc \
+      websockify \
+      ca-certificates \
+ && rm -rf /var/lib/apt/lists/*
+
+# noVNC ships /usr/share/novnc/vnc.html; alias to index.html so / works.
+RUN ln -sf /usr/share/novnc/vnc.html /usr/share/novnc/index.html
+
+EXPOSE 6080
+
+COPY entrypoint.sh /entrypoint.sh
+RUN chmod +x /entrypoint.sh
+
+CMD ["/entrypoint.sh"]