docs: GHCR tags semver-formatted (0.1.0, not v0.1.0)

docker/metadata-action's semver template strips the v-prefix per Docker
image convention (matches postgres:16, redis:7, etc.). Update README +
compose snippet so users pull what we actually push.

README.md

@@ -17,7 +17,7 @@ Open-source backup agent for the [Backupy](https://backupy.tronosfera.ru) backup
 ```yaml
 services:
   backupy-agent:
-    image: ghcr.io/tronosfera/backupy-agent:v0.1.0
+    image: ghcr.io/tronosfera/backupy-agent:0.1.0
     restart: unless-stopped
     environment:
       BACKUPY_SERVER_URL: wss://backupy.tronosfera.ru/agents/connect

docker-compose.example.yml

@@ -0,0 +1,32 @@
+# Backupy agent — paste-ready compose snippet.
+#
+# 1. Sign up at https://backupy.tronosfera.ru
+# 2. Dashboard -> Agents -> Add agent. Copy the one-time key.
+# 3. Save the key in `.env` next to this file:
+#       BACKUPY_AGENT_KEY=bk_agent_xxxxxxxxxxxxxxxxxxxx
+# 4. docker compose up -d backupy-agent
+#
+# The agent connects out to wss://backupy.tronosfera.ru — no inbound
+# ports needed.
+
+services:
+  backupy-agent:
+    image: ghcr.io/tronosfera/backupy-agent:0.1.0
+    container_name: backupy-agent
+    restart: unless-stopped
+    environment:
+      BACKUPY_SERVER_URL: wss://backupy.tronosfera.ru/agents/connect
+      BACKUPY_AGENT_KEY: ${BACKUPY_AGENT_KEY}
+      # Set to "true" to skip Docker socket discovery (jobs still work,
+      # but no auto-detection of databases running on this host).
+      # BACKUPY_DISABLE_DISCOVERY: "false"
+    volumes:
+      # Read-only socket for Docker discovery. Drop this volume mount if
+      # you don't want the agent to enumerate sibling containers.
+      - /var/run/docker.sock:/var/run/docker.sock:ro
+      # Persistent state (BoltDB queue + last-seen offsets).
+      - backupy_agent:/var/lib/backupy
+    # The agent runs as uid 1000 by default and is otherwise unprivileged.
+
+volumes:
+  backupy_agent: