Introduce the Go backend (netwatch-server) with an HTTP API that
accepts telemetry reports and persists them as zstd-compressed JSONL
files. Reports are buffered in memory and flushed to disk when the
buffer reaches 10 MiB or every 60 seconds.
- Add prettier (4-space indents) and reformat all files
- Add Makefile with test/lint/fmt/fmt-check/check/docker targets
- Add MIT LICENSE file
- Add REPO_POLICIES.md
- Fix Dockerfile: listen on 8080 with PORT env var via envsubst
- Restructure README.md with all required sections
- Set up pre-commit hook (make check)
- Update .prettierignore, .gitignore, .dockerignore
