Shared-server build safety

Keep Coolify server concurrent builds at 1 (previously 2).
Do not run manual Docker builds on the production VM alongside deployments. Validate locally first; then push once and let the webhook build finish.
The Docker builder caps Next page-generation workers and Rayon/libuv pools at two. Node subprocesses have a 1536 MiB old-space ceiling. These are not a hard total-memory limit: Bun, native allocations, and separate processes add overhead.
Build controls are restricted to the builder stage; application runtime is unchanged. The final image must pass the Sharp WebP smoke test.
If memory pressure remains high, move builds to a separate builder rather than increasing concurrency or running more diagnostic builds on the live VM.