move worker startup logic from server.ts to runtime.ts for better modularity
add worker-loop-policy.ts for loop control abstraction
delete legacy unit tests under tests/unit/ related to compute worker and control-plane
add vitest config and test directories for compute-core and compute-worker
add vitest workflow for CI
update package.json scripts for new test commands and add vitest as dev dependency
BREAKING CHANGE: worker entrypoint is now compute/worker/src/runtime.ts instead of server.ts; legacy Playwright-based unit tests for compute worker are removed in favor of Vitest
