Switch Lotus Cinny from nightly dev to stable-release fork workflow

- Replace nightly build script with daily upstream release checker
  (cinny/upstream-check.sh) — posts to Matrix as LotusBot when a new
  cinnyapp/cinny stable release is published
- Add cinny/lotus-build.sh — merges latest release tag into the lotus
  branch, builds, deploys; triggered via !cinny-update webhook
- Fork lives at code.lotusguild.org/LotusGuild/cinny (lotus branch, v4.11.1)
- deploy/hooks-lxc106.json — adds cinny-build webhook endpoint (port 9000)
- Update landing page: "dev branch / nightly" → "Lotus fork / stable releases"
- Set LotusBot avatar on @hookshot_tinker-tickets

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

deploy/hooks-lxc106.json

@@ -14,5 +14,21 @@
         }
       }
     }
+  },
+  {
+    "id": "cinny-build",
+    "execute-command": "/usr/local/bin/cinny-build.sh",
+    "command-working-directory": "/opt/lotus-cinny",
+    "response-message": "Cinny merge + build triggered",
+    "trigger-rule": {
+      "match": {
+        "type": "value",
+        "value": "a82340fc2f07e6afda097494c34aa3a4877924932a0b063a76106fdab9816ec6",
+        "parameter": {
+          "source": "header",
+          "name": "X-Build-Token"
+        }
+      }
+    }
   }
 ]