feat: add release workflow, packaging script, usage docs and acceptance checklist

README.md

@@ -2,4 +2,30 @@
 
 My personal used local/offline kanban.
 
-WIP.
+- Cross-platform desktop app (Windows / Linux / macOS) built with Avalonia.
+- Git-like storage: the board lives in a `.ykanban` folder inside the project
+  folder it manages; start it with `ykanban <path>`.
+- One board per workspace with columns, cards and colored tags; strict search
+  expressions (`tag:bug OR title:login`); Markdown export.
+- English and Simplified Chinese interface; light, dark or system theme.
+
+See **[USAGE.md](USAGE.md)** for installing, starting YKanBan, backups and
+Git, and the full search syntax.
+
+## Building
+
+Requires the .NET 10 SDK.
+
+```sh
+dotnet build
+dotnet test
+dotnet run --project YKanBan -- <path>
+```
+
+Release archives for win-x64, linux-x64, osx-x64 and osx-arm64 are produced
+by the manually triggered workflow in `.github/workflows/build.yml`;
+`packaging/package.sh` packs one published RID.
+
+## License
+
+MIT