docs: publish Tend Compose continuity evidence

Export the reviewed allowlisted snapshot from private source commit 07c1655921f21ee5e4fc4d85639d199e8867b17d. This records the Docker Compose activation, schema-compatible rollback, and stateful migration resource findings from Observatory Preview 19 dogfooding.

AI-Assisted: OpenAI Codex
Signed-off-by: Cole Speelman <crspeelman@gmail.com>

examples/server/example-singleton.service

@@ -0,0 +1,19 @@
+# SPDX-License-Identifier: 0BSD
+[Unit]
+Description=Example singleton site
+After=network.target
+
+[Service]
+Type=simple
+DynamicUser=yes
+ExecStart=/opt/example-site/current/example-site
+EnvironmentFile=/etc/tend/environment/example-site.env
+Environment=EXAMPLE_LISTEN=127.0.0.1:8092
+NoNewPrivileges=yes
+PrivateTmp=yes
+ProtectSystem=strict
+ProtectHome=yes
+Restart=on-failure
+
+[Install]
+WantedBy=multi-user.target