Return a real note's slug when present (instead of a synthetic folder `index` slug) in FileTrie.slug and add a unit test to assert that behavior. Expand README with a repository map, local development quick start, build/test instructions, where-to-edit guidance, and troubleshooting notes. Update the Windows helper script (scripts/quartz/quartz.ps1) to prefer the bundled portable Node/npm runtime when available and pin npm's cache to .npm-cache inside the repo for reproducible local runs.
