Prepare btcprice for Kubernetes deployment

CLAUDE.md

@@ -10,8 +10,7 @@ proxies live price data from btcdata over WebSocket.
 - `cp .env.example .env` — optional; `.env` is `-include`d, so a missing one is not fatal
 - `make run-local` — Same, but with `BTCDATA_URL=$BTCDATA_LOCAL_URL`
 - `make tailwind` — Watch Tailwind CSS for changes
-- `make test` — Runs `pytest tests/`, but there is no `tests/` directory yet and pytest is not
-  in `requirements.txt`
+- `make test` — Installs test-only dependencies from `requirements-dev.txt` and runs `pytest tests/`
 - `make venv` — Bootstrap the virtualenv without starting the server
 
 ## Docker
@@ -27,11 +26,17 @@ Docker runs alongside local dev on different ports:
 `btc-network` (`docker network create btc-network` once), and btcdata must be started from
 `../btcdata`. Inside the network btcprice reaches it at `http://btcdata:${DOCKER_BTCDATA_PORT:-4102}`.
 
-Note: `Dockerfile` bakes in a stale `ENV BTCDATA_URL=http://btcdata:4101`; compose always
-overrides it, so it only matters if the image is run outside compose. `ENV PORT` is likewise
-unused — the port in `CMD` is hardcoded.
+The image does not set `BTCDATA_URL`; deployments must provide it. `BUILD_SHA` is embedded as
+`APP_VERSION` and exposed at `/api/version`. The port in `CMD` is hardcoded to 4040.
 
-## Deployment
+## CI/CD
+
+`.gitea/workflows/build.yml` tests pushes to `main` and `v*` tags, then publishes immutable
+linux/amd64 images to `harbor.pmagnus.cloud/btcprice/btcprice`. It embeds the short Git SHA as
+`APP_VERSION`. CI has no Kubernetes credentials; the planned Flux deployment belongs in
+`magnus/deploy` once the shared GitOps gate is complete.
+
+## Legacy deployment
 
 `./deploy-citadel.sh` — build locally for the remote's arch, `docker save | ssh docker load`,
 `docker compose up -d --no-build` in `/home/pmp/apps/btcprice` on citadel (192.168.50.195).
@@ -51,6 +56,8 @@ Mirrors `../elprice/deploy-citadel.sh`; no registry.
 - **Styling:** Tailwind CSS v4
 - **Data backend:** btcdata (separate service at `BTCDATA_URL`, default `http://localhost:4100`)
 - **No database** — all data comes from btcdata
+- **Probes:** `/api/health` is process-only liveness; `/api/ready` checks btcdata with a 3-second
+  timeout; `/api/version` exposes the build identifier
 
 ### btcdata connection