feat: playground static site with cursor webhook deploy

Scaffold nginx + deploy-hook stack for playground.schwenk.online,
Gitea cursor workflow, directory-based public/ content, and boka
bootstrap via git clone.

Co-authored-by: Cursor <cursoragent@cursor.com>

hooks/hooks.json.template

@@ -0,0 +1,32 @@
+[
+  {
+    "id": "deploy",
+    "execute-command": "/etc/webhook/deploy.sh",
+    "command-working-directory": "/repo",
+    "include-command-output-in-response": true,
+    "trigger-rule": {
+      "and": [
+        {
+          "match": {
+            "type": "value",
+            "value": "refs/heads/main",
+            "parameter": {
+              "source": "payload",
+              "name": "ref"
+            }
+          }
+        },
+        {
+          "match": {
+            "type": "payload-hmac-sha256",
+            "secret": "${WEBHOOK_SECRET}",
+            "parameter": {
+              "source": "header",
+              "name": "X-Gitea-Signature"
+            }
+          }
+        }
+      ]
+    }
+  }
+]