Fix two findings from adversarial IX-perspective audit

- create_task.py: add MITM risk warning to --insecure flag help text;
  common home-user pattern (self-signed cert) exposes API key in transit
- install.sh: replace bare systemctl restart with explicit failure check
  that prints a recovery hint when middlewared fails to start post-install

patch/create_task.py

@@ -195,7 +195,9 @@ def main():
     p.add_argument("--api-key", default=None, metavar="KEY",
                    help="TrueNAS API key — System → API Keys (required except for verify)")
     p.add_argument("--insecure", action="store_true",
-                   help="Skip TLS certificate verification (self-signed certs)")
+                   help="Skip TLS certificate verification (self-signed certs). "
+                        "WARNING: exposes your API key to network interception. "
+                        "Prefer adding your cert to the trust store instead.")
 
     sub = p.add_subparsers(dest="cmd", required=True)