[Chore] Drop unused Xvfb from the worker image

[roomote-roomote]

Opened on behalf of Matt Rubens. Follow up by mentioning @roomote-roomote, in the web UI, or in Slack.

Related issue

Internal worker image cleanup after retiring the headed desktop/VNC stack. No linked issue.

Why this PR exists

• A maintainer explicitly invited this PR in the linked issue or discussion
• I am a maintainer / this is internal Roomote work

What changed

Audited the worker image after VNC/desktop removal. KasmVNC, XFCE, and related desktop packages were already gone. This change drops the remaining unused xvfb package from apps/worker/Dockerfile, locks that absence into the existing desktop-runtime regression test, and bumps the worker runtime schema version so cacheable images rebuild.

Intentionally kept:

• Chromium/X11 shared libraries and fonts needed for headless agent-browser
• DISPLAY env passthrough (still an allowlisted runtime env var)
• /sandbox/.vscode as a legacy provider/snapshot path identifier
• Preview-proxy /websockify routes (preview WebSocket protocol, not a VNC server)

How it was tested

• pnpm exec dotenvx run -f .env.test -- pnpm --filter @roomote/compute-providers exec vitest run src/adapters/modal.test.ts (31 passed)
• Pre-push suite: oxlint, residual lint, check-types:fast, knip

Checklist

• The PR title follows the repo convention: [Fix], [Feat], [Improve], [Refactor], [Docs], or [Chore] followed by a user-facing description
• This PR is small and scoped to one change
• pnpm lint and pnpm check-types pass locally
• I added tests or included a clear manual validation note above
• I removed secrets, tokens, private keys, and customer data from code, logs, and screenshots
• If this change should appear in the changelog, I ran pnpm changeset

[roomote-roomote]

1 issue outstanding. See task

• apps/worker/Dockerfile:191: The ARM64 worker image still installs xvfb. .docker/sandbox/install-browser-agent.sh:195 runs playwright@1.57.0 install --with-deps chromium; Playwright always adds its tools dependency group, whose Ubuntu 24.04 ARM64 list inherits xvfb. The new source-text assertion cannot detect this transitive install. Please avoid or remove that package on the ARM64 path and verify the built image rather than only scanning the Dockerfile.

_{Reviewed 207ec0e}