feat: implement Havenllo single-board kanban (Go+SQLite backend, Preact/Vite frontend)

- Single fixed 'Haven' board: lists (To do/In progress/Done) + cards, no multi-board
- Go 1.24 backend, CGO-free modernc.org/sqlite, embedded SPA, REST /api
- Preact + Vite + TS frontend, native HTML5 drag-and-drop, optimistic UI, dark Haven theme
- PVC (nfs-client) for SQLite, root container on NFS, simple nginx ingress havenllo.haven
- Dockerfile multi-arch build, Gitea CI via pipeline-actions@main

README.md

@@ -0,0 +1,52 @@
+# Havenllo
+
+Havenllo is a small, single-board kanban app for the Haven homelab. It serves a
+Preact SPA and a same-origin Go/SQLite API from one binary. On first start it
+creates the fixed **To do**, **In progress**, and **Done** columns.
+
+## Local development
+
+Use a writable database path outside the default container location:
+
+```powershell
+$env:HAVENLLO_DATABASE_PATH = "$PWD\havenllo.db"
+go run ./cmd/havenllo
+```
+
+In another terminal, run the frontend development server:
+
+```powershell
+Set-Location web
+npm ci
+npm run dev
+```
+
+For the embedded production bundle, run `npm run build` in `web/` before
+`go build ./...`.
+
+## Verification
+
+```powershell
+go test ./...
+Set-Location web; npm ci; npm run build
+Set-Location ..; go build ./...
+```
+
+## Container and deployment
+
+Build and push the multi-architecture image on `docker-build.haven`:
+
+```sh
+docker buildx build --platform linux/amd64,linux/arm64 -t git.ivanch.me/ivanch/havenllo:latest --push .
+```
+
+Or push `main` / dispatch the Gitea workflow. Apply the manifest and restart
+the deployment:
+
+```sh
+kubectl apply -f deploy/havenllo.yaml -n default
+kubectl -n default rollout restart deployment/havenllo
+```
+
+The app is available internally at `http://havenllo.haven`.
+