Add README

README.adoc

@@ -0,0 +1,34 @@
+= labelprint
+
+Unified UI for printing labels/stickers:
+
+* Native ZPL printing to a Datamax-ONeil thermal barcode printer
+* A proxy/switcher in front of three https://github.com/DL6ER/brother_ql_web[brother_ql_web] instances, one per Brother QL printer
+
+== Routes
+
+* `/` -- upload a PDF and print it (ZPL)
+* `/upload` -- upload form
+* `/test-print` -- print the bundled test label
+* `/brother` -- pick which Brother QL printer to proxy to
+* `/brother/select` -- switch the active Brother QL printer
+
+== Running
+
+[source,shell]
+----
+bundle install
+bundle exec ruby app.rb
+----
+
+Requires `config.json` (see printer definitions inside) and a `.session_secret` file (random string, not committed).
+
+== Deployment
+
+Runs as `sinatra.service` (systemd) on `rpi-printserver.local`, under RVM (`rvm default do bundle exec ruby app.rb` -- always uses whatever ruby is currently the RVM default, no manual bumping needed).
+
+`.gitea/workflows/deploy.yaml` deploys on every push to `main`: SSH into `rpi-printserver.local`, `git pull`, `bundle install`, restart the service.
+
+== Dependency updates
+
+`.gitea/workflows/renovate.yaml` runs Renovate on a schedule (Monday 06:00 Europe/Bratislava, or manually) to open PRs for outdated gems and GitHub Actions. See the "Dependency Dashboard" issue for current status.