ci: restore Docker daemon access for E2E validation

[moncher-dev]

Problem

Docker E2E validation for #902 could not start because the run host could not connect to unix:///var/run/docker.sock.

Evidence

• docker compose -f docker-compose.e2e.yml up -d --build && docker compose -f docker-compose.e2e.yml exec -T symphony-e2e node /app/e2e/host-dynamic-tool-e2e.mjs failed before image startup.
• Isolated retry: docker compose -f docker-compose.e2e.yml up -d --build failed identically.
• Error: Cannot connect to the Docker daemon at unix:///var/run/docker.sock. Is the docker daemon running?

Expected

The CI/run host should expose a functioning Docker daemon so TC-19 and TC-20 black-box validation can execute.

Scope

Environment/infrastructure follow-up only; no source failure was observed. The full unit suite, lint, typecheck, and build passed for #902.

[moncher-dev]

Duplicate of #914 — same condition (Docker daemon unreachable at /var/run/docker.sock inside the Symphony worker environment, black-box gate exits on its prerequisite check). Consolidated there and assigned to @hojinzs as a host/execution-environment decision.