feat: publish Gamertan Tend preview source

Sanitized root snapshot from private source commit a72903c63e1753f9e6ffbf40453c0830bdfc05c5 and tree 295641e67eef5979da76746d8ae271249568263e. Private development history and workflows are excluded by the exact allowlist.

AI-assisted: OpenAI Codex helped implement, test, and audit this preview.
Signed-off-by: Cole Speelman <crspeelman@gmail.com>

examples/singleton/tend.json

@@ -0,0 +1,24 @@
+{
+  "schema_version": 1,
+  "service": { "name": "example-site", "allowed_host": "example.test" },
+  "build": { "package": "./cmd/site", "binary": "example-site", "branch": "main" },
+  "deployment": {
+    "strategy": "singleton_candidate",
+    "root": "/opt/example-site",
+    "lock_file": "/run/lock/gamertan-deploy.lock",
+    "state_file": "/opt/example-site/tend-state.json",
+    "health_path": "/healthz",
+    "readiness_path": "/readyz",
+    "candidate_timeout_seconds": 30,
+    "smoke": [{ "path": "/", "contains": "Example site" }],
+    "singleton": {
+      "unit": "example-site.service",
+      "address": "127.0.0.1:8092",
+      "candidate_address": "127.0.0.1:18092",
+      "listen_env": "EXAMPLE_LISTEN",
+      "environment": {},
+      "current_link": "/opt/example-site/current",
+      "previous_link": "/opt/example-site/previous"
+    }
+  }
+}