readme: add debian/ubuntu and windows setup

README.md

@@ -3,10 +3,44 @@
 Festival drink-sale tracker. See [PLAN.md](PLAN.md) for architecture, [NOTES.md](NOTES.md)
 for the original requirements, and [TODO.md](TODO.md) for deferred work.
 
-## Dev
+## Toolchain setup
+
+Requires Node.js 20+ and pnpm 9+. Native SQLite bindings install from prebuilt
+binaries on x86_64 / arm64 — no compiler needed for most setups.
+
+### Nix (Linux / macOS)
 
 ```sh
 nix develop          # node 20, pnpm, sqlite, build deps
+```
+
+### Debian / Ubuntu
+
+```sh
+# Node 20 from NodeSource
+curl -fsSL https://deb.nodesource.com/setup_20.x | sudo -E bash -
+sudo apt install -y nodejs
+sudo corepack enable             # provides pnpm
+
+# Only needed if a prebuilt better-sqlite3 binary is unavailable for your arch
+sudo apt install -y build-essential python3
+```
+
+### Windows
+
+Install Node.js 20 LTS via the official MSI from <https://nodejs.org> (this
+also installs the optional "Tools for Native Modules"). Then in PowerShell:
+
+```powershell
+corepack enable                  # provides pnpm
+```
+
+Use PowerShell to set env vars on the same line, e.g.
+`$env:ADMIN_PASSWORD="changeme"; pnpm dev:server`.
+
+## Dev
+
+```sh
 pnpm install
 ADMIN_PASSWORD=changeme pnpm dev:server   # http://localhost:3000
 pnpm dev:client                            # http://localhost:5173 (proxies /api, /admin)