Homepage (TDD slice 3): the real services.json + schema tests

Red tests first (the old services.json was an object, not the new list schema).
- tests/homepage_config.bats: the config is a JSON list; every entry has
  name/category/probe; category is user|admin; method is tcp|http; a
  showLink entry has a url and a status-only entry does not.
- shared/homepage/services.json: the real fleet. User: SearXNG, ComfyUI,
  OpenWebUI, Gitea, Calibre-Web, RomM, Copyparty, Plex, Jellyfin. Admin:
  Hermes, Grafana, Prometheus, Loki, node-exporter, alloy, Caddy, dnsmasq,
  Gluetun (wip - a tunnel has no simple local port), the two LLMs, mariadb,
  valkey, Postgres. Ports confirmed from the repo config (compose/quadlet).
  docs fields are empty for now (the /docs/ workstream fills them as each
  service goes active).

tests/homepage_config.bats

@@ -0,0 +1,41 @@
+#!/usr/bin/env bats
+# Seam: shared/homepage/services.json — the service config the checker reads
+# and the pages render. It must be a JSON list; every entry carries name,
+# category, and a host:port probe. category is user or admin. method, when
+# present, is tcp or http.
+
+load helpers
+
+@test "services.json: valid schema" {
+    python3 - "$REPO_ROOT/shared/homepage/services.json" <<'PY'
+import json, sys
+path = sys.argv[1]
+try:
+    data = json.load(open(path))
+except FileNotFoundError:
+    sys.exit("services.json not found")
+assert isinstance(data, list), "top level must be a list"
+assert data, "the list must not be empty"
+for svc in data:
+    for field in ("name", "category", "probe"):
+        assert field in svc, f"{svc.get('name', '?')} is missing {field}"
+    assert svc["category"] in ("user", "admin"), svc["category"]
+    if "method" in svc:
+        assert svc["method"] in ("tcp", "http"), svc["method"]
+    host, _, port = svc["probe"].rpartition(":")
+    assert host and port.isdigit(), f"bad probe {svc['probe']}"
+PY
+}
+
+@test "services.json: every user service has an Open link, status-only backends do not" {
+    python3 - "$REPO_ROOT/shared/homepage/services.json" <<'PY'
+import json, sys
+data = json.load(open(sys.argv[1]))
+for svc in data:
+    show = svc.get("showLink", True)
+    if show:
+        assert svc.get("url"), f"{svc['name']} shows a link but has no url"
+    else:
+        assert not svc.get("url"), f"{svc['name']} is status-only but has a url"
+PY
+}