chrome-service: size headed Chrome window to fill Xvfb (noVNC cut-off)

The noVNC view showed the browser in the top-left with the rest of the
framebuffer black. Cause: Chrome launched with no --window-size, and there's no
window manager, so it opened at its profile-persisted (smaller) size inside the
1280x720 Xvfb. Add --window-size=1280,720 --window-position=0,0 so the window
fills the screen on every launch (fresh pods/profiles too). Live windows were
already resized via CDP as a stopgap.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

stacks/chrome-service/main.tf

@@ -252,6 +252,8 @@ resource "kubernetes_deployment" "chrome_service" {
               --disable-dev-shm-usage \
               --password-store=basic \
               --use-mock-keychain \
+              --window-position=0,0 \
+              --window-size=1280,720 \
               about:blank
             EOT
           ]