Releases: tag each healthy deploy vMAJOR.MINOR.PATCH; /health and node checkin report versions (node-26#49)

VERSION holds MAJOR.MINOR (1.1). The build job works out the next patch
(scripts/next-version.sh, integer count) and stamps it into c2-core as
DRB_VERSION, which /health returns. The new "Tag release" job tags the
commit only after the deploy job succeeds, so a failed deploy's number is
reused. Node checkins carry `version`, stored on the node doc.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

drb-c2-core/tests/test_versioning.py

@@ -0,0 +1,24 @@
+"""node-26#49 — releases are visible: /health reports the server's, checkin carries the node's."""
+from unittest.mock import AsyncMock, patch
+
+import pytest
+from fastapi.testclient import TestClient
+
+from app.internal.mqtt_handler import MQTTHandler
+from app.main import app
+
+
+def test_health_reports_the_release():
+    with patch("app.main._VERSION", "1.1.4"):
+        body = TestClient(app).get("/health").json()
+    assert body["version"] == "1.1.4"
+    assert "git_sha" in body
+
+
+@pytest.mark.asyncio
+async def test_checkin_stores_the_node_release():
+    with patch("app.internal.mqtt_handler.fstore") as fs:
+        fs.doc_get = AsyncMock(return_value=None)
+        fs.doc_set = AsyncMock()
+        await MQTTHandler()._handle_checkin("n1", {"name": "Pi", "version": "1.1.10"})
+    assert fs.doc_set.call_args[0][2]["version"] == "1.1.10"