Pin Pi server stable image

Server/docs/raspberry-pi-5-docker.md

@@ -12,6 +12,9 @@ Files used for this deployment:
 ## What This Runs
 
 - QSfera server from this `Server` source tree.
+- A pinned production image tag by default: `qsfera-cloud-server:7.0.0-rpi5-stable`.
+- Build metadata injected into the binary through Docker build args:
+  `QSFERA_VERSION`, `QSFERA_EDITION`, and `QSFERA_BUILD_DATE`.
 - QSfera config persisted under `/etc/qsfera` inside the container.
 - QSfera data persisted under `/var/lib/qsfera` inside the container.
 - Host-side config and data paths controlled by `QSFERA_RPI_CONFIG_PATH` and
@@ -26,6 +29,8 @@ Files used for this deployment:
 3. Use a 64-bit OS. The compose file sets `platform: linux/arm64`, and the Dockerfile builds with `TARGETARCH=arm64`.
 4. Put `QSFERA_RPI_CONFIG_PATH` and `QSFERA_RPI_DATA_PATH` on durable storage, not on a nearly full SD-card root filesystem.
 5. Set `OC_URL` to the public HTTPS URL used by clients and the reverse proxy.
+6. Keep `QSFERA_EDITION=stable` and a concrete `QSFERA_VERSION` for production
+   rollouts. Leaving those unset falls back to the defaults in the compose file.
 
 ## Start
 
@@ -36,6 +41,13 @@ cp .env.example .env
 docker compose -f docker-compose.rpi5.yml up -d --build
 ```
 
+Verify the image metadata before rollout:
+
+```bash
+docker compose -f docker-compose.rpi5.yml build
+docker run --rm --entrypoint /usr/bin/qsfera qsfera-cloud-server:7.0.0-rpi5-stable version --skip-services
+```
+
 ## Stop
 
 ```bash
@@ -82,6 +94,7 @@ container uses:
 
 - host config: `/mnt/data/qsfera/cloud-server/config`
 - host data: `/mnt/data/qsfera/cloud-server/data`
+- image: `qsfera-cloud-server:7.0.0-rpi5-stable`
 - public URL: `https://qsfera.kusoft.xyz`
 - loopback port: `127.0.0.1:9200`