Collapse Dockerfile.web / Dockerfile.collab / Dockerfile.mcp into a single
docker/Dockerfile with shared `deps` stage and `web` / `collab` / `mcp`
runtime targets. BuildKit hashes the deps stage identically for all three
targets, so `pnpm install` runs once instead of three times in parallel —
fixes the OOM kill on the Coolify host (CT 107) during `docker compose build`.
Both docker-compose.yml (local dev) and docker-compose.coolify.yml now
select services via `target:` instead of separate dockerfile paths.
Made-with: Cursor